I can't tell you how many times I've gone to clean something to avoid writing. If there is anything writers loves more than writing, it's avoiding writing. No amount of deadlines, no amount of "my publisher/agent" is waiting, and generally no amount of self-recriminations, can get those words on paper.
And it's a fine line. There ARE legit chores to do. Get groceries, take the dog for walkies, call the accountant, load the dishwasher, and all those shows piling up on the DVR.
Sometimes, at least in my case, no matter where I am on a project, beginning, middle, or end, sometimes I have to nerve-up in order to sit down and write. I have to marshal the courage. It's not easy. Sometimes it takes days, or weeks to pick back up where I left off. Sometimes I can't find the words. Sometimes, I look at the manuscript and then go clean the kitchen.