There is something simple you can do to ease osteoarthritis if you already have it, and reduce your risk if you don't.

A recent study shows that nearly two in three obese people will develop osteoarthritis. It's a painful, degenerative condition and can result in reduced mobility, knee replacement surgery, even disability. Losing weight can be the single most important thing you do for your knees -- every pound you lose reduces four pounds of pressure on your knees.

Exercise is also vital. If your joints are sore, try swimming or water walking. Other low impact activities such as walking may also be helpful. You can also ask your doctor for advice on appropriate physical activity.