Understanding the mechanisms by which physical activity is influenced is particularly relevant for health promotion efforts aimed at women, who display lower levels of physical activity and may experience more barriers to exercise than men. This study examined the number of motives for exercise and the number of reasons for previous quitting as predictors of exercise behavior. Specifically, the cognitive complexity of motives for exercise and reasons for quitting, as indicators of exercise-related memory associations that reflect cognitive structure, were evaluated. In a sample of 394 women aged 17-54, number of reasons for quitting did not predict current exercise level. However, more elaborated memory networks for motives were highly related to current exercise behavior, except among women with high Center for Epidemiologic Studies Depression Scale scores. These results support the predictive superiority of positive over negative memory associations found in studies on attitude accessibility in other behaviors, such as substance use, among women of normal mood and suggest a moderating effect of depression.