I've done it. Finished the book and sent it off, only one day late. As Simon said, I should have expected problems when the deadline for a book about ghostwriting was Halloween!
While I was working on it I wrote every day, even weekends, and now I've got into the habit of writing every day. I took one day off after completion and tidied my writing room. That's when I found a children's book that needed revision. So that's what I'm returning to every day now. I don't want to lose the habit so I must keep feeding it.
By the way, the book, Ghostwriting, is out in February, can be ordered from Amazon and gives loads of way for writers to ghostwrite and make extra money. It's not all about celebrities and their life stories.