[Mary] This is Mary Robinette Kowal with Writing Excuses. So we are on the 16th. You should have probably around 26,000 words... 27,000. In that range. I am doing NaNoWriMo this year.
The interesting thing is, I wrote Shades of Milk and Honey, which was my first published novel, as a NaNoWriMo book.
Around this point, every time I've done it, I hit the "what am I going to do next?" The fatigue begins to set in.
You have two choices right now. You can decide that you are realy going to buckle down and get through the difficult spot, or you can decide that your goal is to just get words on the page and to practice having your butt in a chair.
If you take that route, the way to up that wordcount is to start describing things. Describe them in complete, ridiculously overwrought detail.
What you're doing here, you're basically letting go. You're letting go of structure and you're saying, "I'm going to practice, this week, my description."
You may cut all of these words later. You may move them to different parts of your book, which is actually what I wound up doing with mine.
But just today, if you're fatigued and you have nothing else in your brain, sit down and describe in copious, exacting, painful detail, using as many thesaurus words as you can...
Bad writing, basically, is what I'm advising you to do right now.
Describe the room that your character is in.
Have fun! Go write.