Self-Determination Theory (SDT)

A theory that proposes that people’s actions and motivations become integrated with their personality and growth needs when they fulfil needs of competence, relatedness, and autonomy. Self-determined behaviours are intrinsically motivating and contribute to growth and well-being. See also self-concordant goals.

A theory that suggests that when people have their needs for competence ("I can"), connection ("I belong to/am part of...") and autonomy ("I have the freedom to...") met, their behaviours and actions reflect expressions of themselves and contribute to their growth and well-being.

Reference:

Ryan, R. M., & Deci, E. L. (2000). Self-determination theory and the facilitation of intrinsic motivation, social development, and well-being. American Psychologist, 55(1), 68-78. https://doi.org/10.1037/0003-066X.55.1.68