What can improve your mood, boost your ability to fend off infection, and lower your risk for heart disease, diabetes, high blood pressure, and colon cancer? The answer is regular exercise. It may seem too good to be true, but it's not. Hundreds of studies conducted over the past 50 years demonstrate that exercise helps you feel better and live longer. This report answers many important questions about physical activity, from how your body changes through exercise to what diseases it helps prevent. It will also help guide you through starting and maintaining an exercise program that suits your abilities and lifestyle. Throughout, you'll find advice on staying motivated, measuring your progress, and being a savvy consumer of fitness equipment, as well as tools and tips designed to help make exercise work for you.