You don't want to stop typing. But you've got nothing to say. So what you do is, you start typing anyway and you see where you end up. And the funniest thing happens. You actually figure out stuff to type. Now, don't get me wrong. The stuff you type doesn't make sense. It doesn't fit in your story. It does nothing for your plot, it doesn't build suspense, it does nothing to resolve conflict. More likely, you just let your eyes roam around your writing space while you describe the stuff you see. Like:
Need to clean the litter box after I meet this stupid daily word goal. What is that next to the litter box, is that a candy wrapper? When did I eat candy? Wait, I think a better question is, when did I last eat something that wasn't candy? Also, did I know I had this many coffee mugs? I see three on top of the TV, all in various stages of emptiness. There's mold floating on one of them, that must have been from my first 1,667 words. Which one of these coffees is hot, I wonder? I'd really like a drink of coffee, but I can't pick up my hands from the keyboard long enough to take one because I'm in the middle of a stupid word war and I've only got 45 seconds left and I keep losing and I really need to win this one and nobody needs to know I described my disgusting, filthy living room that has been completely neglected during November. How do they know this isn't what my character's living room looks like? It could be. Nevermind I'm writing a dystopian novel set in 2811 and there are no living rooms anymore. These word war people don't know that! Also, where's the dog? Have I seen the dog today? Have I walked the dog today? Is there a chance the dog has been swallowed alive by that teetering pile of dirty laundry? Dirty laundry! There's still dirty laundry in the future, right? Okay, that's where Joe-Bill and Lucy-Ellen meet, they meet at the laundromat. Okay, I got this. Lucy-Ellen walked into the laundromat (note: figure out what a futuristic washing machine looks like later) and her eyes are immediately drawn to the dark figure folding a pair of (note: figure out what futuristic boxer shorts look like later) in the corner of the (note: are there corners in the future? Maybe all the buildings are round. Like the inside of a coffee mug. Wow, I really wish I could stop typing and drink my coffee. Wait, why do I have a World's Best Grandma coffee mug on my table? Did my grandma come by? I don't remember seeing my grandma. Is there a chance my grandma has been swallowed alive by that teetering pile of dirty laundry?) "Hey, there," Lucy-I-forget-the-rest-of-her-name says.
And that's when the timer goes off and you stop writing and start frantically feeling two dozen coffee mugs until one of them is warm, while doing some exploratory poking of the laundry pile with your toe.
You've just done two things:
1. You've written. Badly. Very, very badly. But a minute ago your character was alone in her (note: decide what houses have instead of living rooms in the future) and now she's in a laundromat meeting her love interest. So, believe it or not, in your caffeine-induced haze of keyboard-vomit, you actually did move your story along a little.
2. You've just added 388 words to your novel.
This is what NaNoWriMo is all about.