How Do I Know What I Think Until I See What I Say?

I'm in the middle of revision. Again. I'm always in the middle of revision, if you want the honest truth: as a fast writer, someone who screams through a first draft and puts stuff like [INSERT DRAMATIC SCENE HERE] in my drafts, the moment I put something down on (figurative) paper, I'm already revising. Really, my writing is, like, 80% revision, and I have no fear of it. But sometimes, I get tired. We all do. As I talked about here, it's really important that the author isn't the one to give up on a book before anyone else does, but that's sometimes hard to remember the fifth (or eighth, or tenth) time through a manuscript. And, on top of being tired, there are the doubts. Because the fifth (or twelfth, or fourteenth) time through the book, there are moments when I look at the book and I think "jesus, this isn't very good." Unlike weariness with a project--which can be fought through--there's nothing to really do about the doubts. I can