get a lot of cardio...do things for distance; if u cant run for a half hour, try walking that time. try to increase ur heart rate to where u know ur getting a good workout. and if ur up for it, run
Jog 2 minutes, walk 2 minutes, jog 3 minutes, walk 3 minutes, sooner or later you ll work up to jogging 30 minutes straight and you ll have a body to die for.