One of the areas of healthcare development in Russia today is improvement of the emergency medical care system. Medical workers constitute a special social category, whose professional activity is of the critical significance, as it aims to preserve, support, develop the health both of individuals and of society at large. Emergency medical services workers perform their professional functions under difficult conditions. Their jobs involve significant psycho-emotional and physical overload caused by a variety of stress factors: highly intense work, unpredictability of events, the need for prompt decision-making in conditions of uncertainty and with time at a premium, an increased responsibility for providing healthcare, etc. Daily psycho-emotional and physical burdens impact significantly their productivity, their efficiency in delivering services, the reliability of their professional activities, and their quality of life.
Studies of the professional activity of emergency medical service workers [1–8] cover the urgent problem of stress.
One of the most important qualities of specialists performing critical work, including emergency doctors, and the most important factor for the reliability of their professional work is the psychological stability of the personality in maintaining optimal working parameters (efficiency, vigilance, resistance to interference, etc.). Researchers emphasize that the more difficult the situation, the more the efficiency of the activity will depend on psychological stability rather than professional skill .
The term `stability' is firmly established in psychology. Zavarzina cites as an example 19 terms she found in the literature referring to the concept of `stability': stability of the psyche, the personality, personality traits, mental characteristics and behavior; stability of professional activity, orientation, and motivation; mental, neuro-psychological, volitional, emotional, emotional-volitional, psychological, socio-psychological, and moral-psychological stability; resistance to stress, distraction, and burdening .
Analysis of the literature on psychological stability shows that most researchers define it as psychological readiness to perform professional duties under any conditions. Psychological stability can be examined in the professional duties of a manager, an executive, a judge, a bodyguard, a medical worker, a soldier, etc., but always in reference to specific conditions related to their professional activities .
Psychological stability is viewed by Markelova  as the professional qualitative integration of the personality, defined by a system of interrelated personal qualities, professional activity, and socio-psychological factors. Psychological stability is determined by objective factors (the requirements and conditions of professional activity) and subjective factors (professional training, proficiency, personal characteristics, motivation to perform a professional task).
Antsupov and Shipilov  define psychological stability as an integrative personality formation that preserves the optimal functioning of the psyche during frustrating and stressful exposure to difficult situations, that is not an inherent property of the personality, but is formed in the course of personality development. These authors maintain that human psychological stability depends on the type of nervous system, personal experience, professional training, skills and abilities, and the developmental level of the basic cognitive structures of the individual.
Ponomarenko and Zavalova , exploring the psychology of pilots' behavior in an emergency and the problems of flight safety, demonstrate that safe behavior in extreme conditions is ensured not only by vegetative reactions, but also by needs, motivations, volitions, worldview, and other personal characteristics.
Components of psychological stability include activation, motivation, and cognitive, emotional, and volitional components .
According to a survey by Markelova (12), the motivational component of psychological stability in the military professional activity of future reserve officers is characterized by their emotional and value-oriented attitude toward military professional activity. They have a positive attitude toward the profession, believe in its necessity, identify with the profession, and view it as a calling, based on a special spiritual, moral, axiological, and conceptual state.
Analyzing the research findings, we have proposed that one of the determinants of psychological stability in the professional activity of the emergency medical services workers is the motive of service.
The Objective of this study is to substantiate the psychological content of the motive of service as a determinant of the psychological stability of the emergency medical services worker.
We conducted an overview-analytical study, systematized existing theoretical insights and empirical information, identified the dominant foci of scientific discussion, and substantiated our scientific position on this psychological category.
To process the findings, we used the content analysis method.
3. Results and Discussion
The extra-psychological content of the concept of service
To understand the motive of service, a review of the extra-psychological and psychological content of the concept of service is needed.
Theoretical analysis of research on this problem revealed that the concept of service is used in the Russian language and Russian literature in several domains:
In everyday usage, the concept of `serving' (sluzhenie) has a special semantic meaning in the Russian language. Nowadays, the term `serving' is considered old-fashioned, and in modern dictionaries it is identified as `archaic'; therefore it is appropriate to consider its meaning in earlier editions of dictionaries.
The concept of sluzhenie derives from the word sluzhba (service), meaning the organization of any activity .
The term `service' (sluzhba) is used:
• similarly yet somewhat differently from the terms work, labor: `to take someone into service', `travel on service business', `service duties', `place of service', `enter the service', `leave the service', `be in somebody's service', `put something into service', `service entrance', `service performance', `serving the people', `servant of the people', etc.
• in many idiomatic phrases: `not as a service, but as a friend'; `serving faithfully and loyally'; `old serviceman'; `do a disservice'; `to serve the cause, not the individuals'; `service to the motherland'; `serving the people', `servant of the people', etc.
The term `serving' (or `ministry') is traditionally used in religious and theological literature to refer to the public ministry of church ministers, from John the Baptist and Jesus Christ to the present day  and as a pastoral, ecclesiastical ministry of clergy: `divine service', `church service', `to attend service in church', etc.
The social domain
This includes the broad concept of social service. Social, in the Explanatory Dictionary of the Russian Language by S.I. Ozhegov, is defined as public; relating to people's lives and their relationships in society .
Broadly speaking, social service is a voluntary, socially significant activity that aims to contribute to finding solutions to social issues. The concept is illustrated by such categories as: social position, social environment, social conflicts, socially active groups, social security, social environment, etc. There is a rather large literature devoted to social service as a form of charity, charitable activity, and the most attention was traditionally paid to it by religious and theological writers, as well as scholars in the philosophical, social, and historical sciences. Since the 1990s, several dozen religious studies by religious, historical, and legal scholars have been conducted in Russia on the origins and traditions of domestic philanthropy, Christian principles and social ministry in the Russian Orthodox Church, and state-confessional interaction [17–22, 14] and others).
There are two areas of social service: the resolution of social problems and the socialization of citizens.
The collocation `social service' is most frequently used to define the social activities of religious organizations and confessional alliances, and as a form of selfless charitable aid by volunteers.
Religious organizations, with up to a hundred years of formal recognition of religious social work, are committed to the common internal understanding of the attitude of workers toward their work as a service to God and Man. The core of the social service of religious personages is the ministry to God and the salvation of one's own and one's neighbor's soul through medical and religious care to the afflicted (the sick, the orphan, etc.) . In Church activity, nursing and home health-care define social service as helping the sick, the leper, the outcast, the suffering.
Social service is present in all major religions and has many similar characteristics.
Antonova  considers social service as a special kind of social, non-religious activity of religious communities, based on the oldest religious tradition, that of selfless aid to the needy and destitute.
Ustinenko  defines social service as a historic collectivity of organized forms of social activity by religious organizations, which is an integral part of the realization of religious doctrine and consists in acts of compassion and charity toward specific individuals as bearers of the image of God.
Zubanova [19,20] defines `social service' as a synthesis of the multifaceted activities of the Russian Orthodox Church, expressed in an impact on social well-being, the social stability of society, its spiritual and moral atmosphere.
Social service also flourishes as a form of selfless charitable aid by the volunteer to needy, vulnerable, and unprotected categories of citizens, a voluntary contribution to the development of the public good [19,20].
The term `volunteering' refers to unpaid, conscious, and voluntary activities to benefit others. A volunteer can be anyone who wants to devote his/her free time to voluntary work.
Volunteer activity is a form of social service carried out with the free will of citizens, aimed at the selfless performance of socially significant services at the local, national, or international level, and contributing to the personal growth and development of the citizens (volunteers) fulfilling this activity (Federal Law, 2015).
Social service on the part of adults and adolescents who have experienced addiction, within the framework of their medical-psychological-pedagogical, social, and occupational rehabilitation, was studied by Kolesnikov and Smirnova , Osipova , and others. The rehabilitation process here is aimed at creating a therapeutic environment: the absence of violence, psychological support, fostering higher feelings, spiritual development of one's awareness of one's strengths and capabilities to help those who are weaker, and helping the needy through social service .
By definition, social service is a voluntary, socially significant activity that aims to promote the resolution of social problems. Social service has a deep ethical and psychological-pedagogical basis – a sense of duty, compassion for one's neighbor, striving for constant personal growth .
According to Reshetnikov , social service can be presented as an ideology based on the protection and assistance of the socially vulnerable part of society, contributing to the development of new political institutions, social structures, social culture, enshrined in the public consciousness and supported by sociopolitical practice.
Thus, the collocation `social service' is used in the domestic philosophical, historical, and social sciences as a historically developed collectivity of organized forms of social activity of religious (confessional) organizations, which is an integral part of the practical realization of religious doctrine and comprises acts of compassion and charity toward specific individuals in the form of direct assistance to the poor and needy, as well as in creating certain conditions for the social rehabilitation of the needy members of society.
Regulatory and legal contexts
The state civil service of the Russian Federation involves professional service activities of citizens (Federal Law, 2004). In colloquial Russian, the abbreviated name gossluzhba is used: employee of the civil service, civil servant.
The terms `serving' (sluzhenie) and `service' (sluzhba) are used to specify:
• a state governance board, an agency that has certain functions: tax service, diplomatic service, border guard service, customs service, federal security service, foreign intelligence service, special service, sanitary and epidemiological service, statistical service, migration service, social service, etc.
• a special domain of work, an institution, department or subdivision in an enterprise: chief mechanic service, chief power engineer service, communication service, weather service, meteorological service, air meteorological service, line service (railway); emergency service (in a municipal economy); ecological service, electric service, veterinary service, etc.
The service of statesmen, including tsars and emperors of the Russian Empire, is of great historical importance.
The culture of public service is a forgotten genre of Russian life. To revive, to cultivate, to support and, finally, to raise the meaning and significance of serving the Fatherland not only in military affairs is one of the most important tasks of a far-sighted state policy.
`This is not about regalia, orders or ranks, but about building a state organism. In this sense, examples of selfless service of officials of the 19th century take on a special value' : Nicholas I , the Romanovs , Gorchakov A.M. , and others.
Also the term `service' refers to professional military activity: military service, guard service, general military service, active military service, term of service, service people (in Russia of the 14th to 18th centuries, this was a common name for persons obligated to perform military or administrative service for the State (31). In military units: railway service, communication service, medical service, etc.
Thus, the concept of `serving' (sluzhenie), as well as that of `service' (sluzhba) preceding it, has a special meaning in the Russian language.
To understand the essence of the concept of service means to study its extra-psychological content in everyday usage, in religious contexts, in the social domain, in regulatory and legal contexts.
The psychological content of the concept of serving
Serving means working for the sake of something, for the benefit of someone or something .
According to Bezrukova , serving is the unselfishness of socially valued motives; somebody's help or support; strict, precise, dedicated performance of direct professional functions; the performance not of an obligation, but from an internal civic conviction.
It is a high duty of a citizen and a Christian who does not stoop to flattery, gain, and careerism. In this sense, we speak of servants of faith, science, art, etc.
In the psychology of labor, service is considered a calling, a reflection of an emotional, value-oriented attitude to professional activity in various areas of work:
• For a doctor, this is service to the people, dedicated and selfless service to one's profession, wholehearted and selfless performance of one's professional and civic duty ;
• Vasiliev  considers the profession of a psychotherapist to be service by a soul, to serve life, to study life;
• For a librarian, it to serve the cause of interethnic cooperation and the formation of a common identity of all Russians as citizens .
Nowadays, the concepts of serving the cause of science, art, people, etc., are subject to desacralization. Modern market relations are based upon individualism, competition, rivalry, a system of ratings on which the financial well-being of employees depends. This means that collectivism, cooperation, altruism, unselfish help are no longer regarded as virtues, but as signs of the person's lack of pragmatism, and sometimes even stupidity .
However, the professions of a doctor, paramedic, nurse, teacher, rescuer, social worker, social care teacher, psychologist are among the caring professions.
For those in the caring professions, helping becomes one's job, and from the category of virtues it moves to the category of professions, and service is the supreme motive of helping behavior.
Among the motivating factors that lead a person to engage in professional activities, Ilyin  identifies the following:
• motivations of a public nature (awareness of the need to benefit society, to help others [by teaching children, treating patients, national defense, etc.], a social attitude on the need for labor, etc.);
• receiving certain material benefits for themselves and their families, earning money to meet material and spiritual needs;
• meeting the need for self-actualization, self-expression, self-realization: The person cannot be inactive by nature, and his nature is such that he is not only a consumer, but also a creator. In the process of creation, he gains satisfaction from creativity, justifies his existence.
Research conducted in the UK in 2006 showed that the reasons people choose to become a doctor are: a desire to help others, striving for respect in society, striving to feel needed/ indispensable, striving for scientific activity .
Similar motives, along with intellectual incentives, were also found in other studies among university applicants and students [43–51].
Of all the motives, the strongest is the striving to help people [44,52,46,47,50,53,54]. Arshakuni  confirmed the special importance of the principle of service as a factor of personal growth and moral and spiritual well-being of students entering the caring professions.
The motive of serving belongs to the category of genuinely altruistic motives, when a person tries to contribute to the benefit of society as much as possible, without thinking about private gain. Altruism is mostly considered from the psychological viewpoint as selflessness, conscious and voluntary service to people, striving to help others, to contribute to their happiness out of love, devotion, loyalty, mutual assistance, sympathy, compassion. In some cases, the altruist shows total self-sacrifice, self-imposed limitation, and sets aside his own happiness, interests, and desires. One interpretation of the phenomenon of altruism asserts that there are special altruistic norms of the personality. Altruistic motivation is the basis for helping behavior at the highest moral level [56,57,40].
Thus, a desire to help, to serve people, referred to as 'the motive of serving,' relates to higher motives. The motive of service as a psychological category has not been explored either in domestic or international psychological science.
The motive of service as a manifestation of an individual's altruistic orientation gives a moral vector to professional behavior and is a system-shaping element in the motivational component of the psychological stability of the medical worker. Proof of the truth of these assumptions is the prospect for our further research.