This publication summarizes what is known about the influence of regular physical activity on the health and quality of life of older individuals, addressing both the acute effects of a single bout of physical activity and the more persistent, long-term effects of sustained participation in exercise and physical activity. Section 1 discusses the physiological benefits of regular physical activity, focusing on cardiovascular function, blood pressure, blood lipids, muscle strength and endurance, flexibility, and balance. Section 2 discusses the psychological benefits of physical activity, noting information in a related table that discusses immediate and long-term effects. Section 3 focuses on general psychological well-being, including depression and anxiety, and cognitive functioning. Section 4 discusses the social implications of regular physical activity, referring to a related table that discusses immediate and long-term effects. Section 5 examines who should be physically active. Section 6 focuses on physical activity programs for older adults, discussing the activity mode, training frequency, duration of exercise, and intensity of exercise. The paper concludes that participation in regular physical activity is associated with tangible benefits for almost all older adults. It examines the considerable speculation about why so many seniors choose not to be active and notes the need for additional efforts in this regard. (SM)