It's really difficult, but I have tried to get myself into the habit of doing whatever it is I hate most first instead of leaving it until the last minute. It takes a lot of self-discipline, especially at first, but after a while it gets a little easier. Just don't think about it and jump right in--then you will spend less time and energy dreading it. If I absolutely can't concentrate on something because my brain is determined to think about other stuff (typically, whatever I'm obsessed with at the moment), then I give myself a set amount of time to do what I want first--a half hour (or however long) of playtime, then work. Or I try to find more interesting ways to do whatever it is I don't want to do--for example, if I'm supposed to study for a class and I don't feel like going over my notes, I will try to find something interesting about the topic and google it. That way I'm sort of learning what I am supposed to but it doesn't feel so mind-numbingly dull.
Also, I try to study more efficiently so I have more free time. There are plenty of online study skills tutorials out there that give helpful tips for that sort of thing, and some of them are quite helpful. I flunked out of college in my first semester, so when I went back I was determined not to make the same mistakes again. I utilized the people at the university study skills center and it made a big difference. Time management is very difficult for me, but I've gotten better at it over time--working to develop good habits is critical, and it will save you a lot of stress in the long run.