Some highly intelligent people simply need new challenges. So maybe you don't need to change yourself so much as embrace this new-challenge-seeking behavior as one of your strengths.

As to finding something you love, for a lot of people the problem really isn't the finding. There is something they love, and the hard part is finding a path to the doing of it -- to dropping what they're currently doing, and finding an easy viable way to do the other thing while paying their rent and other bills. And honestly, this is usually made easier by money. If you could stockpile a "stake" and then take some time off to explore only things you're deeply interested in, that might help. Another avenue toward that might be living someplace cheaper, so the money piles up quicker, ultimately giving you more flexibility and freedom to pursue things you love.

Along with this, it's important to be honest with yourself. If you can really get in touch with what you like and don't like about the fields you've been in -- those are the truest clues for what you'll want to do. (I mean, your only other option is to talk to other people doing many different things, until you hear about something that also sounds interesting to you.)

I guess the last bit of advice is have hope. Because that's where it starts.