As you guys might like big boobs(breasts) or bodonkadonks(ass) in a gal, I myself believe the male body can be extremely sexy with the right type of muscles in them.
Why? I don't know exactly why.
It may have to do with the masculinity, proof that the man in question is strong enough to protect you and your children or maybe that they are fertile with loads of testosterone.
It may have to do with the fact that the male penis is also a muscle, the firmness of the male body reminds women of a firm male penis. Thus women may find the muscles in a male body, especially when she has the chance to touch them, arousing.
In this sense I do not agree with Germaine Greer, saying we should also admire the teenager boy's prettiness. I think we on the contrarily should admire and enjoy the firm mature male body. I mean like Will Smith in "I Robot" when he's topless, it really takes my breath away.
now tell me that you don't fancy this.... come on!