Otherwise, it may be time to find some new friends. Effective Studying Whole books have been written about this, so I can't cover all the details important to learning effective studying skills. It's not something they ever teach you, but it is something they should teach. As in the first point about reducing your stress levels, scheduling time to study is an important aspect to effective studying. While you can do it on the spur of the moment or whenever the mood hits you, I think you'll find the mood isn't hitting you often enough to keep up with all the things you are expected to learn in school.
Some people have a real problem with sitting down for an hour or two and studying every day.
Okay, fine then. Then, keep to your word. Rewarding yourself for your accomplishments in studying can be a very powerful motivator. You're studying, but you come across a section or equation or something which you just can't make heads or tails of. Unfortunately, you know something related to it is going to be on the next exam.