It's hard to say what's the biggest turn-on, but one person's
post reminded me of a huge one...
I just absolutely love it when a girl heads to the squat rack or
to the dumbbell pit and starts training her ass off. There is
something extremely sexy about a girl who's confident enough
to bust her ass on squats rather than on the stairmaster.
This is, of course, assuming she's somewhat attractive to begin
with...
I dunno if it's just me, but an average girl gets bumped up, and
a hot girl becomes irresistable, if I see them doing that.