BJJ (and other martial arts) can also be good for developing social connections. You spar with a variety of people, and have the time before and after class to actually speak with them. You may have to hunt around for a good gym with a more positive community (I've had the pleasure of finding one, and the displeasure of being at one with people who took themselves too seriously), but it's pleasant.
But it's always better when the exercise itself is semi-social, not a solo activity. Cycling groups can work well or meeting people, but cycling on its own doesn't really help. Same with running and swimming.
