The point is, any physical activity is better than none for the overweight crowd, though some people might need to work up to an hour or more per day. A doctor can offer guidance on an exercise routine and provide a referral to a nutritionist, since it's difficult to lose weight without emphasizing both exercise and a healthier, lower-calorie diet. An increasing number of gyms and YMCAs have programs targeted specifically for those who are overweight or exercise newbies.

I'M THIN ALREADY

Wearing a size 2 is no guarantee of good health. It doesn't mean your heart is in good shape or that you are strong enough to lift your toddler without hurting your back. For example, a British study published last fall in the International Journal of Obesity found that lean people had healthier levels of "good" cholesterol and triglycerides regardless of exercise. What's more, the lean study participants who exercised three times a week had healthier levels of total cholesterol and lower levels of "bad" cholesterol than did their sedentary counterparts. Thin people may also have high blood pressure, which exercise can help lower. And thin women are at increased risk of osteoporosis. Weight-bearing exercise, like walking, running, or aerobics, and strength training are key to helping them maintain strong bones.

I'M NOT A GYM RAT

If you fear the gym because of the intimidation factor, remember what Dear Abby says about church: It's not a museum for saints; it's a hospital for sinners. Same goes for the gym. It's not just for people with perfect bodies. Many chains, from Crunch, with its "No judgments" philosophy, to Curves, which targets women who are just starting to exercise, actively seek out customers of all shapes and sizes. (It's good business, too, since few people are perfect 10s.) "The key is to go to a place where you feel comfortable," says Pulido.

That means shopping around for a place to exercise like you would for anything else. Visit a number of gyms and ask for a free trial membership. Prices vary widely depending on the level of luxe. In addition to affordability, seek a facility that has appealing classes and the kind of equipment you intend to use. No use in paying for a gym that doesn't have the rowing machine you like. Some gyms also offer outdoor classes for those who can't stand being cooped up inside.

Those who think a gym means being confined to the treadmill or stationary bike should take a second look. Clubs offer a variety of classes, from circus acrobatics to Afro-jazz dance, and anything that gets you moving and your heart beating faster is fine. The Life Time Fitness chain has rock-climbing walls, great for improving strength, and racquetball courts alongside the usual equipment. Velocity Sports Performance, a national chain, offers speed and agility classes aimed at improving sports performance. "People have grown tired of just sitting on a piece of equipment and pushing out more reps," says founder Loren Seagrave.

I HAVE ARTHRITIS