Physical exercise, I find hiking does wonders. Something to get the heart rate up and if you manage to get up a hill, and there is sunshine, whereas there is fog in the valley, sun is also an important part. Sun stimulates vitamin D production.
Eating right, cutting out fizz drinks and positive mental attitude. It is still early days for you, cycling is normal. Soon you will be on the upswing and cycles will not be so severe and they will be spaced more apart.
Also getting enough sleep is important and quality of the sleep is paramount. Go to bed relaxed and early (pref. before 11 PM).
And of course GAL. Do stuff for you. Remember that scuba course you wanted to take? Or that trip you've always dreamed about? Go see a movie even if by yourself. Learn to enjoy being by yourself and you will come to realize you will be just fine.
