Various groups representing a number of different perspectives (for example, operational, architectural, community, institutional, and individual resilience) use the term resilience. We define resilience as the ability to withstand, recover, and grow in the face of stressors and changing demands. Physical fitness is one pathway toward resilience because it is associated with many traits and attributes required for resilience. In addition, physical fitness confers resilience because regular exercise and/or physical activity induces positive physiologic and psychological benefits, protects against the potential consequences of stressful events, and prevents many chronic diseases. This article presents a brief historical overview of the health-promoting effects of exercise and physical activity, followed by a discussion on the concept of hardiness and mental toughness and how they relate to resilience and physical fitness; how physical fitness promotes resilience; the clinical implications of a sedentary lifestyle; and the relevance of physical fitness and resilience to Army Medicine's Performance Triad.