Every full moon I must have 1,000 more items than the previous full moon. Since each full moon is about 30 days apart, I must create between 30-35 new flashcards a day (A reasonable amount).
This creates a simple, unchangeable deadline. And because there are no tests to cram for, the deadline is not as scary as a "finals week" deadline might be.
So each time the full moon comes around, it is a constant reminder that I am 1,000 items richer.
(Photo credit: countryfydgirl from Flickr)