It's one thing if a magazine tells you to exercise. It's quite another if your doctor does.

To help yourself stick with a fitness plan, try this: Ask your doctor to "prescribe" an exercise routine and to be specific about it. You'll be five or six times more likely to follow it. Why? Maybe having a doc spell out how exercise can ward off life-shortening diseases hits home in a way nothing else does. You just may find yourself jogging out of the office.

When it comes to motivating people to get moving, the power of doctors is hugely underused. Less than 50 percent of physicians recommend exercise to older patients, according to the latest research -- even though there's plenty of evidence that exercise can prevent or alleviate a bevy of health disorders. And the benefits aren't just physical: The healthier people stay, the less they have to spend on medical care and prescriptions. So for those living a sedentary life, starting an exercise program can end up producing a fatter wallet as well as a fitter body.

Be sure the exercise prescription you get from your physician is detailed -- that's part of what makes it successful. It should cover:

Frequency -- How often to exercise.
Intensity -- How hard to push; start at a comfortable level and work up.
Type -- What to do; usually a mix of aerobic (stamina), strength, and flexibility work, but one type may be especially important for you.
Time -- How long to work out.
Progression -- When to change what you're doing; set some step-by-step goals.
Benefits -- What to expect; be sure you understand the specific ways your routine will help your health.

Then, just follow doctor's orders.