That depends on the type of person you are but some things that might help are exercising (proven to help), eating bananas (they have something in them that makes you feel better, watching anything funny (laughter is the best medicine), hanging out with friends (friends = fun), or just doing things you enjoy. Holps this helps. :)
Cracking down on video games might be a good idea for me if I'm honest. I spend ages on them to distract my boredom but when I come off them I feel really weird.