Try to pick up some kind of sport. Taekwondo worked for me, you just have to conquer the embarrassment of being a beginner among new people, but those communities are usually friendly and get a lot of newbies all the time anyway. No social obligations, just go and do your own thing, over time you'll probably build some relationships as a side effect.

Running was a big help for me too. Again, just gotta get over the initial hump of laziness and being embarrassed at doing something that you're not very good at, until you start to get into it.