Lab sciences. I can read studies and interpret results and analyze statistics all day long, and even distill them into plain English. But I don't have the stomach to dissect a worm, never mind a rat (as my daughter was upset to have missed out on doing in person this week) or, God forbid, a cadaver.
Also, advanced math and physics. When it shifts from the realm of the concrete to the realm of theory, I get lost somewhere along the way. I took statistics for my college-level math because that deals with things I can actually wrap my head around.