Interestingly enough, I've never had this problem, mainly, I think, because I'll read and learn about almost anything. Sure, it's not always worthwhile, and it doesn't always grab you, but you pretty quickly pick up whether you're doing something because you want to be doing it, or because you feel the need to force yourself through it.
If you want my advice, learn about art or literature. Learn to find the nuances and extract meaning out of an author or artists work. I think it's easier with literature (read a few critical commentaries and suchlike, learn about the author, and reread the book a few times) but that's because I never really put much time towards art. The good thing about literature is that it croses all fields, dabbles in everything, and can send you off on tangents of discovery about things you would never have thought of before reading the book.