Physical activity will help you look and feel better. Your skin, hair, posture and muscle tone all will improve. You'll be stronger and you'll have more energy. Activity also helps you avoid depression, stress and boredom. You'll be more alert mentally. Thinking more clearly can even help your grades. And, being active is fun! Exercising to maintain a healthy weight decreases a person's risk of developing certain diseases, including type 2 diabetes and high blood pressure. These diseases, which used to be found mostly in adults, are becoming more common in teens. Callisthenic strength also helps with muscles. Strong muscles are also a plus because they actually help protect you when you exercise by supporting your joints and helping to prevent injuries. Muscle also burns more energy when a person's at rest than fat does, so building your muscles will help you burn more calories and maintain a healthy weight. For my callisthenic strength training for the second three weeks, I tried to maintain at least three to four different types of exercises everyday for at least the minimum of ten minutes. The exercise that I usually did was run in place for at least 30-60 seconds. Another one would be push-ups, which seemed to be the easiest for me, so I would easily knock out 35 (Level 2). The last thing that I loved to do was the jumping jacks, as you can see in my three week contract I always did at least 40 everyday. Considering the benefits to the heart, muscles, joints, and mind, it's easy to see why exercise is wise. And the great thing about exercise is that it's never too late to start. Even small things can count as exercise when you're starting out — like taking a short bike ride, walking the dog, or raking leaves. If you're already getting regular exercise now, try to keep it up after you graduate from high school. Staying fit is often one of the biggest challenges for people as they get busy with college and careers.