When you go on a walk, your mind comes with you. Take that time to think about anything you want! Or listen to other people talk about functional nanotech or whatever else interests you, i.e. podcasts. Reframe going on a walk as the time where you get to listen to podcasts or a time where you're allowed to do nothing with you mind and see where it goes.

I realized this is just advice for myself, so that I'll walk more!