This document discusses cardiac rehabilitation and the effects of exercise. It describes 3 phases of cardiac rehabilitation: phase I focuses on early ambulation and low-intensity activities in the hospital; phase II involves incremental physical activity as an outpatient; and phase III emphasizes long-term community-based or home-based exercise. The benefits of habitual physical activity and exercise are summarized, including increased cardiac output and reduced heart rate, blood pressure, and mortality risks. Contraindications for exercise are also outlined.