What makes your life interesting? What do you get up to that is exciting, different, strange? What do we let ourselves do to get away from the dull, ordinary, the boring?
It might be a cliché to say that this is why some writers write. A writer can live vicariously through his characters. On a basic level, a character in a story can get up to things a writer cannot. Exotic, impossible things. Ride the Orient Express in the late 19th century? Fly a spaceship to the moons of Jupiter? Hunt a woolly mammoth? But they can also do less overt things. Like run for office in their city. Like solve an impossible murder mystery. Like defuse a long-forgotten bomb from World Word II. Or even more subtle things. Standing up to the boss’s boss even though it means instant dismissal. Asking that girl out in high school even if she’s already seeing someone. Probably.
I would go so far to say that a writer must live vicariously through his characters.