Staring at the ceiling is when you think the most.

Try it.

Nothing else to see except for maybe a fan.

Turn it off. Stay focused on nothing.

Let your mind run. Run with it. Don't chase it. It's not lost. It's just exploring. Explore with it. You never know what it might find if you just let it loose; and, if you don't go with it, how will you discover anything new?