Sometimes you start writing something - especially on November 1st - and as soon as you get past the first scene, it's like pulling teeth. Maybe you realize you're not sure how you want to tell it. Maybe there's more research needed than you planned for. Maybe you're stretching every single scene out to ridiculous proportions to get the number of words it calls for on your outline.
The last one happened to me this year. I got frustrated, then I got bogged down. I was depressed about other things as well, which didn't help, but here I was with a daily word count I was expected to hit and a novel begging to be told as a serial that I now suspect will be considerably shorter than 50k words.
Most people will tell you to power through it and keep going, no matter what. If you can bring yourself to do that, then maybe you're still on the right track after all. But after two days of poking idly and not succeeding at the powering through, and knowing that if I keep doing it this way, it's not going to go anywhere, I decided to do something drastic.
I decided to start over on day six with a light, snappy urban fantasy project that I can zip through. It's not high art, but it's fun and I wrote about three thousand words on it today. That's a pretty good sign.
And words on something else? Is better than no words on what I'm "supposed" to be working on.