When you write a scene, try to make sure every character in it, secretly or openly, wants something. Not all characters have to actually know what they want, but they’ll be way more ‘in’ the scene if they’re hoping for some sort of outcome.
Characters who are ‘unmotivated’ can become passive, background deadweights. Or worse, they can make the reader suspect the writer has been lazy or forgetful.
So motivate all characters by thinking about what they want or need from each scene. That way, everyone in your story will seem more alive and real, and so will the scene.
Just ask each character how they want this scene to end. For any who don’t really care about the outcome, consider removing them from the scene altogether.