Elmore Leonard famously said that a story is real life with the boring parts left out. Think of the boring parts as anything that doesn’t relate to or affect your protagonist’s quest. Every single thing in a story—including subplots, weather, setting, even tone—must have a clear impact on what the reader is dying to know: Will the protagonist achieve her goal? What will it cost her in the process? How will it change her in the end? What hooks us, and keeps us reading, is the dopamine-fueled desire to know what happens next. Without that, nothing else matters.
