The best way to lose weight, as I have learned from much experience, is by changing your life-style instead of over-exercising and/or dieting. Try to find things that you enjoy doing that keep you active. You are still very young so you should be having fun and enjoying yourself, not worrying so much about lbs. Some ideas include riding a bike (instead of driving), swimming, dancing, playing sports with friends, and going for walks. If you watch a lot of t.v try to cut down the hours. Instead try to keep busy and make plans with friends. Walk places instead of getting rides. You will start enjoying yourself more and start to feel the lbs melting off while you are having more fun! Enjoy and good luck!
