If you have any love for the refining and shaping process of making a book, revision can be much anticipated. I'm not talking about the early tweaking of individual chapters, which can result in rewriting your opening chapter 1 so many times, you get sick of the book and never write chapter 2. (I've seen this so many times, and it's a sad thing.) Real revision, in my mind, is not that level of line editing but a whole-book reshaping, a re-visioning of the book's purpose, and an attempt to get out of the writer's chair and into the reader's.