Exercise lowers your risk of heart disease by decreasing blood pressure, increasing HDL (good) cholesterol and relaxing blood vessels, and improving blood flow to your exercising muscles. Exercise can also reduce stress. Adding at least half an hour of aerobic (or "cardio") exercise to your day benefits heart health by getting your heart rate up and improving fitness through cardiovascular activities, such as running, swimming and cycling. Weight training helps to reduce body fat and strengthen muscles used in aerobic exercise.