"We now know that exercise is the most underrated health precaution anyone, even those with chronic conditions, can take," says J. Larry Durstine, Ph.D., a spokesman for the American College of Sports Medicine (ACSM).

If you want to keep your heart healthy and help fend off diabetes, 30 to 60 minutes of moderate activity most days of the week should do.

Getting in shape through diet and exercise is rarely a linear process; even the most dedicated person is bound to have setbacks. But by setting realistic goals and facing your fears and stumbling blocks, you can get fit and improve your health as a result.

You know it's important to stay active but still find yourself falling back on old habits. What can you do? Planning for exercise isn't hard if you make it a priority.

You can't walk across a room without huffing and puffing. Your arms get tired unpacking a bag of groceries. You're carrying more and more excess body weight. And you can't remember the last time you got any real exercise.

Working out when you have a serious illness or health problem can be challenging. But for most people who have health issues, exercising can improve their prognosis and well-being. In fact, exercise can play an important role in helping you cope with or recover from a health challenge or accident.

Your exercise time can depend on everything from your work schedule to when your kids get up or go to bed.

To keep yourself entertained and enthused, wear headphones and listen to high-energy music while you work out.

Some excuses—I weigh too much, I'm too old, I have too many health problems—are in themselves strong arguments for increasing physical activity.