That's the whole point of the matter though, isn't it, that if you don't have ambition, then you voluntarily get yourself stuck in a rut of your making. "I'm content in that my life is shitty in X or Y way, but cannot do anything about it".
There was a time when I found comfort in thinking that I would grow up to be "comfortably middle class". My parents disabused me of that notion, and now that I am at that stage, I feel as though there is so much more I can learn and do, instead of clocking in and out day after day.
But hey, if you find happiness in working at a gas station or something, maybe you are more enlightened than I am.