1. Protects against some cancers. Regular physical activity reduces the risk of developing colon cancer and may also help prevent breast and lung cancers.
2. Helps lessen love-handles. Yes, exercise does fight flab, but this is not just a cosmetic issue. Weight gain during adult years may lead to obesity, which increases the risk of developing endometrial, kidney, breast, colon and gallbladder cancers as well as diabetes, hypertension and heart disease. AICR's report recommends gaining no more than 11 pounds during adulthood. Regular exercise can help you meet this goal. More muscle equals a more active metabolism. A higher metabolic rate helps lesson the chance for weight gain and obesity throughout life. Also, fun and active outings decrease boredom and time available for extra snacking or grazing at home.
3. Reduces the risk of heart disease. Aerobic exercise (exercise that gets us breathing such as running, brisk walking, swimming or biking) strengthens the heart and blood vessels, increases HDL ("good") cholesterol and lowers triglyceride levels.
4. Helps lift mood. Thanks to chemicals released in the brain during exercise, you may find feelings of anxiety, depression and mental stress melt away during a workout. These same body chemicals may even reduce pain and induce feelings of happiness and well-being. Greatest improvements seem to come after weeks of regular exercise, so stick with it!
5. Lowers blood pressure. Physical activity can reduce blood pressure that's already high and prevent high blood pressure in the first place.
6. Bolsters the immune system. Regular, moderate activity benefits the immune system, which may mean fewer colds, viruses and infections for you.
7. Reduces the risk of developing diabetes. Exercise improves your body's ability to use the insulin it makes, lessening the chance you'll develop type II (adult-onset) diabetes. If you have type II diabetes, exercise can benefit your condition and may decrease the amount of medication you need.
8. Helps maintain bones and joints. Weight-bearing exercise can help prevent osteoporosis, while a sedentary lifestyle promotes bone loss. Physical activity is important for keeping joints and muscles strong, along with promoting flexibility and balance.
9. Boosts self-esteem. Meeting a challenge, improving health, looking better, feeling stronger, meeting new people... regular physical activity can increase self-esteem in many ways. You can do it!
10. Is fun! If exercise seems like a grind, you just haven't found the right activity. Step aerobics or abdominal crunches may not be your style, so try morning bird-watching rambles, join a mall walkers' club or take a spin around town on your bike.

AICR - American Institute for Cancer Research