Being around other people who are serious helps big time. I don't always need it, but I know the experience is way different if I go to one 24 hour fitness over another or a fitness connection.
At one, most of the people there are pretty focused...so we joke with each other more and all know each other. You don't slack off in a place like that.
No, you don't need it...but it helps.
Then again, like right now while I heal up, I like just being to myself.