On the elevator, I heard someone say “It was the greatest day of my life.”
This got me thinking: What was my greatest day? What does that say about me and how I can use that realization in my writing?

A Great Day Changes You

If a day was the greatest of your life, you must be changed by it. Even if you don’t recognize it at the time, you are a different person.
In fiction, a good story must have characters who change as a result of the situations unfolding around them. A hero who starts and ends a story unchanged makes for some boring reading.
But usually the events that change a character are negative and how that character deals with adversity is what shapes them. In Star Wars, Episode IV, Luke:

  • Loses his aunt and uncle, so goes with Ben
  • Ben is killed and Luke escapes with Han
  • Han takes off, leaving Luke to trust Biggs and Red Leader
  • Biggs and Red Leader are killed (and R2 is blown to hell and Wedge has to leave the formation), leaving Luke alone to blow up the Death Star

Through it all, Luke embraces the Force, hits the thermal exhaust port, and becomes the hero of the rebellion.
But it was hardly “the greatest day of his life.”

A Great Day Defines You

So the greatest day of a character’s life might not be the climax (unless it’s a teen romantic comedy where George McFly knocks out Biff Tannen). So how can the greatest day of a character’s life help your story? If not the climax, then what about the call to action or first disaster?
Call to Action
Call to action is a change to your protagonist’s world that he (I will stay with a masculine protagonist in this example) usually resists. Think Luke telling Ben he can’t go to Alderaan with him. This helps ground the character, making one of his obstacles to overcome his own inertia in life.
By using the greatest day, you show what the character values. Is his greatest day winning the lottery? The day he discovered a favorite author? A drunken bender on spring break?
You also show everything the protagonist could lose.
By showing what’s important to your character and how does he reacts when something changes gives you a tool to reveal a lot about him or her.
First Disaster
The first disaster is what starts the action. For example, Luke’s aunt and uncle are killed, setting him on his adventure with Ben Kenobi.
A better example is Bruce Wayne where (in some iterations) not only are his parents murdered in front of him, he just had a great time at the movies. (Perhaps his greatest day?)
By having the first disaster relate directly to the greatest day, you can take the character through a range of emotions. This runs the risk of being clichéd if done on too grandiose a scale—the Silver Surfer crashes the wedding of Sue Storm and Reed Richards—but this effect can be done on a small scale.
Imagine a bookish girl on the farm, an outsider in her rural community, finally getting a chance to go into town where she visits a second-hand bookstore. She spends the day reading, discovering voices and ideas she’s never contemplated. She vows to return, gathering what meager allowance she has, only to hear the store has closed. How would this change her? What action would she take as a result from a simple, but crushing, event?

What’s Your Greatest Day?

Think to yourself what your greatest day was and what that says about you. What did you learn? How did you change? Why was it so great?
And what did you learn about yourself?
Consider that realization—that introspection—and apply it to how to develop your characters. You’ll probably learn a lot about her or him.