i work out everyday, 1 day i lift (65lbs on a curling bar, 140 n the bench, 20 pushups, and some total gym thing i got) then the other day i workout on my punching bag.
that way i get stronger, a cardio excersise, and i will learn how to fight better.
rowan is right, muscles dont matter that much, if u have some guy that benches 200 and has never fought anyone and another guy who can only bench 110 but he boxes, the boxer will win if they fought.
muscle growth, believe it or not, is a part of puberty...theres a stage where u can actually start building muscles(i think its an earlier stage, but everyone grows at different rates)
and one more reccomendation...if ur cool with some of the football players, ask if u can work out with them and have them show you a few tips or new excersices.
....also rowan, its the lactic acids that build up, not amino acids.
if u ask for my myspace profile url i might just give you it