Now that becomes all you can think about. So you start writing scenes...in your head. You come up with dialogue, even actions, and begin to craft almost this entire novel, inside your brain. You write down one of those scenes, but it doesn't sound the way it did in your head. It actually hurt a little bit. So you go back--I mean, who wants to feel pain? You write and rewrite scenes, still in your head, but every time you write it out, you wince, because it hurt a little bit.
And it becomes this endless cycle of starting to remove the tumor of your story, and then stopping, and trying to live with it again. But once you start to feed the tumor, nurture it, even remove it, there is no going back to the way life used to be. You're stuck with this, and the only way it can end is if you just decide to sit your butt down and remove it, one little bit at a time, gritting your teeth through the poorly worded dialogue, lame plot twists, and undeveloped characters. And when it's done, you can sigh in relief. You've done it--the tumor is gone. You can finally go back to life! At least, until you get a great idea of how to fix that one chapter, and oh, that character could do this, which would totally fix that plot hiccup, and the tumor returns. And this time, the only way to get rid of it is to rewrite, and rewrite your book, until the tumor is gone.
Until one night, you're trying to fall asleep when suddenly you sit up--you've just come up with a fantastic idea!
...Writing a book is like removing a tumor. Thing is, I couldn't stop writing if I wanted to.