Hi unchained_soul -- I don't have a particularly bad past either, and I used to beat myself up for being depressed for apparently no reason. Strangely enough, that didn't help me to get any better :) Everything is relative, and when you deny or suppress your real feelings they can bubble away inside and start to seep out in negative and destructive behaviours, I've found. This site is helping me a lot -- I hope it helps you too.
Good luck :)