Your muscles are active even when you are sleeping. Their cells are still doing the routine activities they need to do to stay alive. This work is called metabolism, and it uses up calories. That can help keep your weight in check, even when you are asleep!

To do most of the strength exercises , you need to lift or push weights, and you need to keep gradually increasing the amount of weight you use.

You can use the hand and ankle weights sold in sporting-goods stores, or you can use things like emptied milk jugs filled with sand or water, or socks filled with beans and tied shut at the ends.

There are many alternatives to the exercises shown here. For example, you can buy a resistance band (it looks like a giant rubber band, and stretching it helps build muscle) at a sporting-goods store for under $10 to do other types of strength exercises. Or you can use the special strength-training equipment at a fitness center.