Abstract: The promotion of exercise behavior is a critical issue in the field of public health, but the existing theories still have limitations in predicting and intervening exercise behavior. Based on the necessary conditions for the occurrence of exercise behavior, this study proposed a determinants model (motor competence, time, motivation, self-control and physical exertion, MTMSP) of exercise behavior. This model illustrated the mechanisms underlying exercise behavior at the individual level, identifying motor competence, time, motivation, self-control, and physical exertion as core determinants, and revealed the interrelations among these factors through a three-tier structure of “prerequisites–dual-process motivation–self-control regulation”. The current study found that the MTMSP determinants model provided a new theoretical perspective for overcoming the intention–behavior gap and challenges in behavior maintenance. Future research could use this model to assess the initial state of the target population, and then design more tailored intervention programs to promote the occurrence of exercise behavior.