Try not to think about what actually makes you "happy" and think of all the things that give you a positive emotion, friends, Hobby's, shows, think of things and write down the ones you dont feel depressed with doing, if you're not depressed while doing it, it's probably a good feeling, right?

Personally when I had to do that I struggled because it was comfortable. If that makes sense. I found comfort in my depression because I had it for so long that genuine happiness was weird to me. It's like an addiction. Maybe somehow you're afraid to be happy because up to this point you've been disappointed. I'm not saying that this is what's best for you but you could try working on noticing where and why you've been disappointed by people and overcome it by putting those situations in perspective. For example, In my situation I was put down by my parents and they never saw me as enough. So instead of working so hard just to be disappointed that they don't see my hard work, I acknowledged my hard work and became proud of myself. Maybe for you it's not the same but there may be a way to work around it. (If this helps, or just helps you think about it, you could bring it up with a therapist and maybe they can help figure out a new homework assignment that may be easier for you.)