I play soccer any chance I get and will play pretty much any sport out there. I have recently taken up squash since the school where I work has some courts. It is hard on the ego when all of the students are able to beat me though.
I am a pretty strong introvert (INTJ - if you're into Meyers Briggs). I am happy to go out, but I then need time to decompress either with a book or by making some music. I think I keep a pretty good balance, but it can be difficult when work gets busy.