I brainstormed all the things that I used to like to do, the things that I've always thought about or wished I could do (but didn't, because I was drinking and/or couldn't afford it, due to spending my extraneous income on alcohol). I wrote them down in a word doc and proceeded to try different ones.
I'm learning that these interests return gradually. Oh, and I did find working out and general exercise to be really rewarding in more ways than one.