Your world, the setting, that place where everything happens. Where characters experience terrible perils and see victory over impossible odds! Is it boring? Is your world stagnate? Does your world change or do only the characters?
These are questions I ask myself when reading or writing or watching a movie. Some Worlds don’t need to change. Others do. Many worlds change, or rather should change, as a result of the actions of your characters acting upon it. Sometimes your characters will change as the world acts upon them. Maybe there’s a tornado or a drought. These might not even be main parts of the story but just things that need to be mentioned to make the world feel real.
Your world is a character and it needs to be developed like one. Otherwise you just have interesting people walking around a blank white page.