FAQ: How do you make yourself write so much and not get distracted?

This question comes most recently from a school visit, but I get variations on it a lot. ("Isn't it hard to make yourself work when there's no one to make sure you're doing it?") It seems like an appropriate post for New Year's Day, when everybody's busy making resolutions and promises to themselves!

The brief answer is: I just do. I make myself work because for me, writing beats any other job I could have. And to make it work I have to work.

But the question's really asking about discipline...