 The primary goal of this study is to determine experimentally the relationship between affective response to exercise and future exercise behavior. A secondary goal is to examine potential mediators and moderators of this relationship, specifically four variables considered to contribute to the volitional control of exercise behavior - planning, attention, resource commitment, and affect regulation. An additional goal is to examine how symptoms of depression might influence the affective response to exercise, and the relationship between affective response to exercise and exercise behavior. 