The Thrill of Beginning
The best thing about struggling through the end of a book is looking forward to the next project. I don't know about other authors, but I always get at least one idea of what I want to do next during the writing of a current project. If the writing is not going well, I gets LOTS of ideas and have to resist the urge to toss what I'm struggling with and switch to one of my bright, new idea.
My current ending has gotten delayed a few days due to real life, but I should be finished by the middle of next week. Then I'll save the manuscript, back it up to several different places and forget about it.
Then the fun begins. I'll start researching my next project. I already have a rough idea of the premise. So I'll spend a couple of weeks, maybe a month, researching all kinds of things.
Than it's back to the current project. Enough time will have gone by that I'll look at it with a fresh eye. I'll be thrilled when I find a particularly good passage and horrified at some of the crap I wrote.
It's all part of the process.