You need aerobic exercise to keep your heart and lungs working their best. But what happens when you ignore aerobic exercise and spend most of the summer playing computer games with your friends?
Chances are, you gain weight. When you try on your jeans for school, you can barely pull up the zipper.
Maybe you turn to your older brother for advice, saying, "I was a couch potato all summer -- and now I look like one! What can I do?"
Your brother responds, "It's simple! You have to move around more...