Whether you're a gym newbie or simply free-weight phobic, get this: Your own body is all you need to build muscle and strengthen bones.

Squats and lunges shape up your legs and butt as you lift your torso, arms, and head with every move. Push-ups, sit-ups, arm lifts, and arm circles strengthen and stabilize the rest of you. Here's a thought to keep you motivated: If you don't do strength-building exercises, you'll lose 5 percent of your muscle every 10 years. And with a no-gym workout, there are no excuses. Try the RealAge 20-Minute Workout.

After age 35, men and women slowly lose muscle mass -- the average woman loses 2 pounds of muscle every 10 years and the average man loses 3 pounds. To stay slim, healthy, and strong, you need to counter that loss. Maintaining muscle mass at any age takes only 10 minutes, three times a week. About the slim part: A pound of muscle uses 75 to 150 calories a day to do its work; a pound of fat needs only 3 calories a day -- it does little to help your body, so it doesn't need much energy to survive. So if you have lots of muscle, you not only stay strong but also burn more calories -- which can mean staying slim, too.