You won't reach the end by making excuses for not writing. You simply have to make yourself write during those times you don't want to produce words.
I suppose that my approach comes from my years as a reporter working on deadlines. You had to produce or else you'd be on the street looking for another job.
Of course, if you're not committed to the project and feel that you've reached a point where your heart, mind or soul isn't into it, then move on to something else.
Many writers (if not all) have given up when they believe they've reached a dead end. I've had a few false starts where the story simply wouldn't advance no matter how much I tried.
But again, I've returned to a manuscript after a year with a different and fresh perspective on the work, and was able to make the needed rewrites to turn it to a novel.
I guess the lesson is to never throw away or delete something if there is a possibility it could be revisited.
But the main thing is to keep writing.
Until the next time...