I’ve taken a 45 min walk everyday for the past 2 months and it‘s fixed something. Don’t know what the science is. Don‘t really care. Bring a notebook with you. Listen to music or just your surroundings. My favorite thing has been catching 6 seconds of the funniest conversation, you’ll never know the rest of. Just noticing more things that you might overlook in a car, or a train, or on a bike. If you’re stressed, angry, sad, confused etc., a walk might not fix you but it will change something!