The paper presents the keynote lecture given at the Interregional Conference "Psychology of motivation in modern social contexts" organized jointly by Tomsk State University and International laboratory of positive psychology of personality and motivation of National Research University Higher School of Economics (Tomsk, July 2016). The paper introduces Self-Determination Theory (SDT) as a contemporary theory of human behavior. The issue of "free will" is discussed from the perspective of psychology of motivation. An integrated multi-level model of human behavior viewed from different perspectives of contemporary science is presented. The main aspects of two of five mini-theories constituted SDT framework are described: an Organismic Integration Mini-Theory, which distinguish different types of regulation (intrinsic vs. extrinsic) and elaborates the Internalization Continuum (from amotivation to intrinsic motivation); and Basic Psychological Needs Mini-Theory, which describes the concepts of three basic psychological needs in autonomy, competence, and relatedness, as analogues of "psychological vitamins" necessive to human growth, flourishing, and optimal functioning. The concept of autonomy and its impact on different types of interpersonal relationships like parenting, teaching, and employer-employee relationships are discussed. The results of research conducted in two Law Schools in the USA are presented. The findings show that autonomy-supporting environment results in student's higher career motivation, better subjective well-being, and higher academical performance, as compared to more controlling environment. The new approach to measuring the motivation to change, proposed by Hudson and Farely (2015), and its implications for measuring the well-being changes, and value changes is discussed.