Math, without a doubt. I'm convinced I'd be going to an extremely prestigious college next year if I wasn't so bad at Math.
And the sad thing is, I'm really not SO bad at it. I have a B in it. But I get A's and A+'s in everything else without studying and working, so a B makes me feel sad inside. Ugh.
I do recall having trouble with Chemistry, because of the math, of course. I used to love Science, but because of that, I decided never to take a Science course again. I guess I was just gifted at Biology, not mathematical sciences. xD
If we're counting PE then, uh... It's a winner. I was the guy who stood on the sidelines smoothing out his clothes and daydreaming I was in a fancy pool.
Yeah, I actually managed to fail PE during high school from staying home "sick" too much. So that.