All jokes aside, walking is way underrated. I should add that walking without headphones, without music or podcasts, is even better.
It's like an extended shower thinking session. It gives all you thoughts a chance to surface and be addressed. You rarely get a chance to be idle and think about things if you don't make time for it. If you walk to work, it's a nice separation between your personal and professional life.
In a way, it's like taking your brain to the park, and letting it run around without a leash for a bit.
Walking in nature is much better. I never regret going a little further out to walk in a nice forest. It's proven to make people happier.