I often lose my momentum after writing about 500 words. To revamp, I do something else for a while: clean the house, grade the papers, cook the food, etc. Then I can move on to the next 500 for the morning. The other day I switched from typing to hand writing to shake things up. (Word Count for Today: 800)
What do you do to keep your momentum?
Especially during a month-long writing spree like NaNoWriMo?