Social sports leagues are also good to help encourage a decent bit of activity as well. For those who have a hard time being motivated to go to the gym and exercise regularly it can be incredibly beneficial to have a group to play some kind of sport with as a habit. Personally I have a hard time being motivated to go to the gym but having a group to encourage you to come out and play a game its a lot easier to be motivated.
You don't have to be good to have a good time.