Hey everyone, im 15, weigh 57kg(126pounds) and am 168cm(5ft5") tall. I have just started exercising using weights mainly workin on biceps, pecs and trying to find something good for my abs. No matter what i do my muscles dont burn longer than an hour or 2 even if i work to exhaustion. Some people i've asked said to use really light weights then do a few hundred reps but id rather not do that cause of the time it would take. For biceps i do about 10x3 hammer or rotating hammer curls, my left arm struggles and cant finish them but never burns. For chest i do 10x3 planshe push ups from my chair and again they dont burn. Any advice? thanks