I need help with suggestions on how to put 20 pounds on of muscle. I'm 15, 5'9 and weigh 140. I currently am doing mostly pushups (diamond and regular) and lifting free weights 20 pounds. After my workouts I drink my mega whey protein shake and eat a full meal. I play varsity basketball and finished up my season yesterday. If any athletic people have advice on how to get my weight up I would accept any advice given.