Evelyn, the wisest member of our critique group (I don't think anyone else in the group will disagree with that assessment) suggested we try to write 100 words every time we sat down and faced those pages. One hundred words is a pretty piddling amount, so of course, if you set that as your task, you will always succeed. Well, nearly always.
This challenge breaks things down into very tiny bites. One hundred words easily becomes 300, 600, or 800. Still not a huge volume, but at least the work progresses. And because it's an easily handled amount, it's not terrifying to sit down to work on. Paragraph by paragraph, page by page, I'm getting there.