i get the feeling i'm doing a boxer's workout totally wrong. we're doing differant muscles differant days, and we usually do two muscles a day. first we did back and biceps (i did hammer curls, but not focus curls), then we did chest and triceps. we work on them one at a time, back then biceps, chest then triceps, is working on them one at a time bad?

also...i get winded easily. when i'm using my punching bag and get really into it, even if i take a one minute break after three minutes, the second time i do it my left jabs are barely at half of what i start at. is there any workout to help here? i've heard of intervals, like 2 reps of 800 meters, 3 reps of 600 meters, 4 reps of 200 meters or something, not possitive, but my friend says i should start on the treadmill first to get my legs in shape, then start doing the intervals.