I think you may be confused about IQ scores. 130-140 is extremely good, in the 98-99th percentile, if I remember correctly. That's smart enough to be a member of Mensa, however, many people will argue that IQ isn't a good measure of intelligence for a plethora of reasons.

That said, I think you are too focused on forcing yourself to learn things, then allowing yourself to enjoy the things you're learning. Don't feel like you have to listen to "intellectual" music or hang out with "intellectual" friends. Give effort, receive results. Even a genius can fail.

I understand being scared of failing - I made it my life's mission in early high school. If I wasn't amazing at it, I wouldn't do it and I sure as hell wouldn't even try to do it.

Work on the things you think you need to work on, but do them in a way you can enjoy. I know I don't have time for solving word or number problems, so every Saturday I do the ones in the back of the newspaper while I drink my coffee. If I think I am going to be waiting somewhere, I bring along something along those lines to do.

As for whether mental illness is harmful to your intelligence... I think some can, and some can help it in a way. I always say being bipolar really sucks but it's good because I understand some things better now than I did before. I've seen the highest of highs, the lowest of lows, and I think it gave me a different perspective on many topics.