Quarter-life crisis caused by not knowing what I wanted to do career-wise. I got my first "real" job and absolutely hated it, I felt hopeless that I'd ever be happy again and in the months of unemployment I had during this time (before finding and after quitting this job) I felt completely worthless because I didn't have a "thing" like everyone else did. I compared myself to the success of others CONSTANTLY. I got out of it by taking a kind of random job that while not something I wanted to do long-term was more related to my natural interests and skills, and after about a year there I had a strong sense of what I wanted next. I took the plunge and went back to school for something I feel extremely passionate about and was lucky enough to find a job at my university, and now I'm happier than I've ever been in my entire life.