I'm a full time student working half-time with major depression. I don't get things done as fast as I could but everytime I do get something (anything) done I try to tell myself that it's a success. I'm on medication so luckily that helps a lot but there was a year when I literally couldn't get myself to go to Univeristy (that's a long story)...so I know how you feel.
I reward myself with stuff (a bookmark, a shirt, a good coffee) and luckily have friends who are very supportive (they know of my condition) so I try to go out with them at least once a week, those meetings also nearly always help.