push ups and sit ups are always going to be the things that effect the most, it's true. they're just amazing, and you can see and feel the instant results. however, in many exercises, you don't even realize you're working your other muscles, because your use of them is not super obvious. however, just training with a rifle (if you do, i trained with an m-16 and walked around with it all day in boot camp) does wonders for your whole upper body. just do it - it can't HURT, that's for sure, and it's not like you could flat out refuse to do them, is it. just let me remind you that there might be a time in which you'd be glad you worked all of those muscles, because when we go out to do very physical things we often find ourselves using muscles we never thought existed. maybe, through this exercise, those would be trained to begin with.