Abandon the idea that you are ever going to finish. Lose track of the 400 pages and write just one page a day, it helps. Then when it gets finished, you are always surprised.
John SteinbeckI have taken as much as six years to prepare a book for writing. There is such a delirium of effort in the production of a book; it's like childbirth. And, like childbirth, one forgets the pains immediately so that when you come to write another one you dare to take it up again. Some precious anesthesia sees you through.
John Steinbeck