This guy? He's a fitness nut on YouTube, and a brony as well (yes, it is real). jaxblade07, in case anyone is interested.
Seriously, people, stop this stereotyping! Haven't you learned by now that it is dumb?! Stereotypes are almost always formed from gossip and generalizations that aren't factual or thoroughly looked over. Get a clue.
I have a couple friends (brothers, in fact), both very muscular and athletic (as in, "I'm going out into the woods to chop up crap with my insanely sharp machete, and try not to cut out my pupil again.") They're both awesome, and guess what?! They DON'T CONSTANTLY TALK ABOUT PONIES. In fact, every brony I know is an awesome dude with plenty of non-pony related hobbies and an actual life.
I think it's time some people on this forum learned some logic, and stopped believing everything they hear, as long as it conforms with their ideals.