The ability to write your own story, is the ability to create your favorite book without even trying because when you start writing, and all of those dreams, fantasies, and memories you've ever had flow out of your mind and into that story. Then that story becomes your own. 
It's your own plot. Your own theme. You create the story as if it's a masterpiece. The story is a way to reimagine a world that you want to create. One that leaves you thinking, creating, and writing. But when that story comes together, that alone is my favorite part.