Organize - work is more interesting if it's easier, and organizing it will make it much easier! Have an assignment notebook where you keep all of your homework and due dates. Keep a calendar for due dates, too, and put alerts into your phone reminding you when to start working on those tests and projects.
Encourage - reward yourself for working. Pick something realistic, like putting money into a jar whenever you complete a study session, then buy yourself something nice when you make a good grade, or go out to dinner to celebrate.
Make it meaningful - find some way to relate your studies to your life so that it's more meaningful to you, and thus more interesting. You'll need math to balance your bank account, for example, or those scientific facts about edible plants will come in handy on a camping trip. You can even make this something silly, like "I'll need to know the countries of Europe in case I'm kidnapped by rabid geography professors and held for ransom."
