One theory of motivation is based on rewards.
If you're shirking your responsibilities, then you must be getting short term rewards without doing your work. I always did HW first, then played later. There was no procrastination. The better I was at HW, the faster it got done, the more time I had later.
A second theory of motivation is to reduce the feeling of a need/urge. i.e. you eat in order to reduce hunger.
In your case, simply look at all the idiots around your school. Although you may be smarter, school will treat you as your grades are and you could possibly have to spend another year with them. The better you do, the sooner you can get out. Secondly, you'll also end up in a shittier college, with shittier people. Yuck.
I dabbled in a bit of psychology. I took a class in HS.