Like a lot of computer folk I spent my days sitting with terrible posture, and I love how it makes my back feel.
If physical exercise is missing from your day, I can tell you that for me, adding it was trans formative. It's much easier to sleep well if you are physically tired too!
In a big city, meetup.com will have a lot of interesting things happening every week, so rather than pick a hobby you might want to just make a point of doing a couple of those a week until you happen on something you want to do again.
I also sing choral music. I've been in some sort of chorus since 7th grade. Enjoyment of music gives me an entirely different sense of satisfaction and pleasure than do my more intellectual interests and I think that's healthy and helpful to being more well rounded.
- Mountain biking - Hike with groups (great way to meet people) - Kickboxing (competitive and strategic) - Scuba diving (cheap adventures) - Gaming