Pilates is based upon a series of controlled movements that are centered around the body's "powerhouse" -abdomen, lower back, and buttocks. With a strong and healthy powerhouse, the rest of the body is properly supported and can move freely. 

Pilates does not stress the body in the ways that lifting weights or other workout methods may, this is why everyone can do it. You'll see your bones strengthen, your muscles tone and firm, and your circulation improve.  But, most of all, as you work out and begin to feel better physically, you will also begin to feel better mentally.