Self-determination theory provides a useful way to understand why some people are regular in their exercise and others are not. Much of the difference is related to where they are on the motivational continuum.
Self-determination theory contends that the primary psychological needs of autonomy, competence and relatedness lead individuals to seek and meet the challenges of life.
The level of autonomy largely distinguishes among the different levels of the motivational continuum.
References: Whitehead, J.R. (1997). Self-esteem in Children and Youth: The Role of Sport and Physical Education. In The Physical Self (Ed. K.R. Fox). Champaign:Human Kinetics.