Somewhere I read that the last 20% of a novel is the hardest part to write. I'm believing that I concur.
Part of it is because you say goodbye to the freshness of your characters--after this it's all editting and revising. Doesn't seem like there's any new surprises. (Unless you want to keep writing the same book for the next twenty years....)
Another part is the 'cleaning up' process. The first half of a novel is about making a mess. The second half is about cleaning that mess up. As anyone with small children (or anyone who has even vaguely seen a small child) knows, making the mess is infinitely easier than cleaning it up. At the end, there has to be a resolution. A raison d'etre.
Right now, I know how it ends. The question is whether or not I can pull it off. Does anyone else know how to handle this? Or should I shut up and just do it?