When I write page 1, I don't know what page 2 is going to be like. I write the book to know what's inside. - Julian Green
Particularly when I write during National Novel Writing Month, I tend to start a story without a clear idea of where I'm going. I get the feeling I've written about this topic before in here, but I'm going to continue anyway. I'm with Julian Green: I write the story to find out what happens. During NaNoWriMo I generally reach a point where I need a plan. The story faucet, up until that point flowing freely, begins to taper off until it becomes a trickle. Then I need to start with the outlining. Where am I going, and why am I in this handbasket? Who's in this story? What important things are going to happen? What needs to happen before I can write The End?
In five years of participating in NaNoWriMo, I don't think I've ever actually written The End. My story may wind itself up, but it's never a total beginning-to-end manuscript on the first of December.
But on my original point: I write to see what happens. That's a lot of what gets me through NaNoWriMo. I want to succeed, I want the purple progress bar, and I want the certificate. I want the satisfaction of having a 50,000 word manuscript in my hand, that tangible, meaty sound it makes when I drop it - thunk - onto my desk. But day-to-day, one of the primary motivators is the same as it is when I'm reading someone else's work: what's going to happen next? Will Sarah and Aristotle escape from the beast? Will Dobroy ever give back that oh-so-important chess piece he took? Can the robot convince the two alien races to live in harmony? Will Hypatia stop being crazy? In order to find out, I had to write. And all of those questions have answers now. Each of them lives in a NaNo manuscript I've completed (except for the first one, which got a sequel of sorts in 2008, bringing its total to 76,000 words).
If you create a story you want to read, you're forced to write it until it reaches an end, or forever wonder what might have happened. Go create a question and answer it. Or wait until November and then do it. I'll meet you there.