Pickup a new hobby - I dove head first into improving my golf game, and try to play at least once a week. It gets me out of the house, sitting at home alone, and gives me something to feel good about, even if its just a good golf shot every now and then.

I think finding something to get you outside is always a plus. I always feel my mood improve when I get out in the sunshine - play fetch with the dog, mow the yard, or take a walk.