This is writing advice that I got from someone else, my week two Clarion instructor, the completely fabulous Jim Kelly. He gave us a list, Jim Kelly's 10 Stupid Plot Tricks, which he then told us to forget immediately.
I am a bad student. I wrote them down.
Most of the time, I forget about them. Plot, for good and ill, isn't something I consciously think about when I write. But the tenth Stupid Plot Trick, I come back to that one over and over again. Here it is:
Write ten endings.
I actually don't think I've ever used this to discover what the end of the story is. I do use it all the time in the middle, though. When I don't know exactly what's right for the story at that point, I make a list of possibilities, and think through what might happen next, and then what each of those "might happens" means for the story as a whole. Sometimes doing this solidifies that my first instinct was right, because it helps me to understand why Possibility A was my gut choice. But sometimes I walk through a number of different scenarios before I get that mental click that tells me that Possibility Q is not only right, but takes the story in a better direction. It's a useful technique for me as a writer because it asks me not to just think about possibilities, but to think about why those possibilities matter, and what sort of consequences they might have.
So there you are. One of the most useful things I've learned about writing. Now, forget that I ever told you.