Calculus.
I breezed through calculus in high school, but I didn’t like it…I found it tedious and uninteresting for the most part (not entirely, but for the most part). Unfortunately, I had a lot of people ask me for help and I just got to do more and more calculus! Ugh… :(
Just math in general too. I can’t say that I don’t enjoy all of it, because I do enjoy some of it. But even though I didn’t take any math classes last year, I was still helping people with math…it just seems to come naturally to me, even though I find it to be largely boring…lol…I’m a word/language/letter person. :)