I'm a seventeen year old, and I have to stop running. Without getting into detail, I basically have always had alot of health problems, and I started running about 8 months ago. It seemed that I was okay, and just recently alot o fmy health problems have been coming back, and my parents (my father is a physician) said no more running. That's fine with me because I never really liked running, I just did it to stay in shape. My questoin is, can I quit and go to another aerobic activity (like bicycling), for a shorter duration and less intensity without gaining weight? I was running 4.5 miles a day, in about 38 minutes, then I walked for the last two. This is too much, I knew I couldn't keep it up forever, and now I HAVE to stop. If anyone could help, that would be greatly apprecaited.