So for the first time in my life, really and truly, I've got a job that I can't weasel out of. That's a bit different from saying "I've got a job I can't quit." I've had those before.
What I mean is...if I fuck this job up, it'll be a real fuck-up. And if I _leave_ this job, it can only be because I genuinely believe that I'm not capable of doing it, that I really did hit my limit. Every other job I've lost, I've always had excuses. I could always tell myself, "Well, it's not like this job should exist anyway."