Because a MAN is what your body and energy scheme is designed to be, being a MAN is whats going to be easy and feel natural. The burden you feel comes from all of the self imposed and externally imposed exigencies, facades, hurts, malfunctioning stuff, eg. neurosis, and you are trying to run a fake alpha persona on top of that, so of course THAT is exhausting. The sensitive man without a backbone, nope, thats not what girls want.