I manage a lot better than most of my friends, but I wouldn't say that I stray away from being overly judgemental on myself. It's one of my biggest flaws. However, if I can't see the merit in my own work at a particular stage, I try to look at stuff I've completed in the past, because I can see it accurately for what it is and appreciate any positive aspects. If I'm worried about how I'm going at school, I also try to look at anything I've done out of school, such as music, leadership, random competitions - things like that.
What probably helps me relax the most is actually socialising with people though. It helps me to view myself as a person, not as the number that I'll ultimately determine my ability to gain a tertiary place. I also have a tendency to talk/laugh way too much, and to be slightly hyper constantly, so I presume that helps me to loosen up and have fun.
I also obsessively write in my blog, and I tend to pour my emotions into that. It's not good in one respect, because I sometimes write things that I normally wouldn't, but it's exceptionally cathartic. Playing violin's good too... it keeps me sane! I used to get to school at 7.30 every day to practise for an hour before class, and I'd always turn up feeling revitalised, alert and relaxed.
In terms of the psychological disorders - I read blogs (which actually sounds slightly stalkerish), and for some odd reason quite a few people divulge their emotions to me. I don't exactly understand why...
But yes. I don't think this list helps everyone... I guess people just have to find something they enjoy which serves as a distraction.