When you enter the ring with an unfinished manuscript, it is a wrestling match. You have got to know the strengths and weaknesses that your opponent (the manuscript) possesses. It's going to slam you hard with its brute strength and batter your ego. Every step of the way it's going to whisper to you that you don't have the strength to prevail and that you should just walk away. It wants you to leave it, as is, in the ring. That's the toughest part because, inevitably, this is true. You have to walk away from it.
The irony is that this beast is all of your own making. All of its power came from you, the writer. All of its weakness came from you, the writer. In the strangest twist of tactics, the manuscript's weakness is its most horrific strength, because they are your weaknesses. Despite all this, you have to squint at this beast through eyes bleary with too much staring at the screen and murmur that over-used heroic action line, "Let's finish this..."
I'm in a twelve round fight with this beast. Twelve chapters of nonstop slugging it out. And there's not a referee in sight.
Just me and a 180 page electro-imaginary beast.