I have the same problem a lot of the time.. and unfortunately I don't really have the answer - still looking for it myself!

I have found that accountability does help though. Is there a friend in your class you can study with or study group you can join? Having someone pushing you to do the work makes a major difference.

The other thing is to do your best to not get behind - keep a schedule of when/what you are going to do and try to stick with it. It tends to hold off the feelings of not caring.