There are times when I do pretty much anything and I say something that I regret after. Usually it was something that is selfish, rude, or just me forgetting to be polite. After that I get into a mental rant where I point out everything that went wrong in that conversation and how I was rude to the person I was talking to. I will start thinking about the future and these different scenarios where the way I act now ruins my life. (The one I have the most often is when I'm in a job interview and the interviewer is asking me what my worst quality is, but I am forced to take a truth serum to answer. I start talking about all of my worst qualities and saying that they shouldn't hire me because I would be terrible for the job, and I always end up crying at the end of the interview.) In real life I start to cry and almost an hour passes before I've calmed down (which just happened now, actually.)
Whenever I feel sad I always think about myself being a failure, or if I don't I think about the people around me realizing what a terrible person I am and leaving me.

(I guess there wasn't really a purpose to this but whatever...)