My best thinking doesn’t happen at my desk. Every morning I go for a 20-minute walk with one rule: no devices. Just walking and thinking. It is reliably when ideas untangle themselves. (And some days there’s a LOT of entanglement.) I have long suspected there is something mechanical going on. Motion seems to free cognition. Which is why I have always wondered about chewing gum. The word ruminate literally means to chew. And there’s something to it, proven by science. A peer-reviewed study...