David Cain describes his mental switch to focus on one tile at a time instead of worrying about the pain of having to clean the whole floor.
As long as zeroed in on the current tile, rather than think about the dozens of tiles I had yet to clean, there was minimal discomfort and no tedium. Whenever my mind started to drift that way, I remembered my elegant strategy: look at a tile, and clean that tile. As far as I could tell, nothing more was required.