There are those pockets of downtime you don't know how to fill.
A minute here. Two minutes there. It's very convenient to pull out your phone and kill those minutes by scrolling through some posts or pictures.
What if for that one minute or two you allowed your mind to wander?
What if you pulled out a notebook and held it open, thinking?
What if an idea popped into your head, and you wrote it down?
Make it a practice to carry a notebook with you, always. Not your phone where you can, of course, type up your idea. Your phone will have all those other distracting things on it. Your notebook won't.
I always carry one on me. And a book. Always a book.