Exercise as a moderator of the stress-illness relation was examined by exploring leisure physical activity and aerobic fitness as potential "buffers" of the association between minor stress on physical and psychological symptoms in a sample of 135 college students. The goal was to gather information regarding the mechanisms by which exercise exhibits its buffering effects. Researchers have examined both physical activity and physical fitness in an attempt to demonstrate this effect; however, whether both of these components are necessary to achieve the protective effects against stress is unknown. This study examined engaging in leisure physical activity and having high aerobic fitness to determine if both were necessary for the stress-buffering effects or if one factor was more important than the other. Findings suggested a buffering effect for leisure physical activity against physical symptoms and anxiety associated with minor stress. This effect was not found with depression. Additionally, there was no moderating effect for aerobic fitness on physical or psychological symptoms. Collectively, the data suggested that participation in leisure physical activity as opposed to level of aerobic fitness is important to the stress-buffering effect of exercise. Implications for exercise prescription are discussed.