Running and doing push ups and sit ups and pull ups and how high you can jump, and sports are different than doing 5 sets of 20 reps with 50 lbs weights. I don't know what you do Walmart (calling you that is awkward) but if you do do weights, take it lightly, don't over do it. You can get a ripped stomach and ripped pecs by doing pushups and sit ups. Let your body grow for 2 or 3 more years then you can start lifting weights, and taking your body to a harsher limit.

I was just like you at 15 (well i was 14 but still) I lifted weights everyday, ran everyday, did pushups sit ups, everyday. I did whatever I could to get stronger, then I learned that's bad for you and stopped. I'm kind of hoping you do the same. Trust me, if you are really into lifting weights, and working out, you only need about six months until you noticed huge differences. I think you can wait until your 17/18