In an attempt to understand the inherent process underlying the regular practice of physical activity, the relationships among subjective norm, attitude, habit, intention, and future behaviors have been investigated in a random sample of 136 University of Toronto employees. For this purpose, leisure-time exercise behavior was measured on two occasions after a statement of intentions had been obtained: 3 weeks later (proximal behavior) and 2 months later (distal behavior). The results of a path analysis (LISREL) suggest that intention is directly influenced by habit and attitude, proximal behavior is the result of habit only, and distal behavior can be explained by a combination of intention and proximal behavior. Subjective norm was not a significant predictor of intention, proximal behavior, or distal behavior. This modeling approach offers a clearer understanding of the dynamics of exercise intention and behavior, strongly supporting the role of habit as a determinant of exercise behavior.