It's all about moderation. Balance the two, Get mad and Be Happy, equalize fun with the work, bad eating with good eating and a lot of walking, exercise and stuff (It doesn't have to be a heavy work out) It will also greatly benefit you down the road.
Improve yourself, learn some skills, pick up writing, learn how to draw, pick up an instrument, make electronic music, lift weights, etc
Fill your life with things that interest you, if nothing interests you, you're not trying hard enough.
An imbalance in these fields will cause an imbalance in both your health and mental health, Moderation.