If you're flagging a bit, try this, sort your Writing Buddies by Word Count -- Highest to Lowest, then try to beat whoever is just ahead of you.

Then do it to the next one. And the next.

Don't have any writing buddies?

Bring up Tim's graph

http://faces.naperwrimo.org/2013/naperwrimo.shtml

and try to beat someone who has written just a little bit more than you. (There's a link on the page to post to the thread to be added to the graph if you're not on it.)

Another trick is to try to get to the next 100 words, or 1000 words before the end of the day. (And then look at your stats page and realize that if you write 325 more words you'll have written over x-thousand for the day. So try for that, and so on. If you like numbers, this can be very motivating.)

I second this. This is what I've done all month and it has really helped me.

If you're really brave, you can taunt the person ahead or behind you and both of you can move quickly with the competition.