I decided today would be "the end" because this date is significant to me. Yet, I sit here and wish I had said more about character development, dialogue, plot and sub-plots, arcs and so many other writing elements I learned at uni and from peers (books, blogs, and my cherished beta readers).
The end comes and shouldn't be prolonged beyond its time. Don't put your story on life support, let it go to resonate in the minds of the readers long after they have read it.
I should add, don't rush the end. Don't leave your readers still hungry for the resolutions left unwritten.
So the end comes. It is short in comparison to the middle, yet it has always been the goal. If you think of a bell curve in statistics, the beginning and end are the outward edges. The middle is the swollen part between them.
Whether the story is "a day in the life" twenty-four hours in a rapid paced adventure of espionage or the saga of a western frontier family, the end is the curtain call. First you finish up with the minor characters, then the next prominent, then the main character and the antagonist. They hold hands and bow. The stage darkens. The curtain closes. Those who 'got' the story sit as the house lights come on and others begin to leave.
They are satisfied. It will be a least a day or more before they pick up their next book and begin the adventure between the covers.
What have you done? You have resolved everything you've mentioned throughout the story. You've used every prop the prop master set on the stage. One by one, each character's quest has been resolved and has helped to carry the main character to their resolution. The music (pace) has been perfect. Every line delivered as intended.
You type, "THE END" and sit back; satisfied, complete as your readers will feel too.