Used to want to do an M.D. Realized I didn't want to be 400k in debt before I'm even a resident. Thought I'd do a Ph.D in chemE, but didn't feel like being underpaid and overworked for 4+ years.
Teaching is rewarding. So is connecting with your fellow students. It was a completely different league at CC vs. Uni. Did a lot of research throughout my undergrad. I still like what I majored in, but it took me a long time to adjust after my personality got absorbed and prepared to get fucked by grad school.