I would find walking in a city to be a barrier to creativity. You have to keep engaging your concious, safety brain to deal with other pedestrians, road crossi

I would find walking in a city to be a barrier to creativity. You have to keep engaging your concious, safety brain to deal with other pedestrians, road crossings and immunize your brain from all the advertising and noise that is trying to penetrate. The ideal walking for me is somewhere outside with fresh air, but without constant interruptions to the flow of walking and thinking. Ideally you want to be able to walk alone, but in a type of daydream where you're thinking about the problem at hand instead of spending many cycles on the process of walking. That means covering a well known route with few interruptions. Luckily for me I have access to this type of environment right near my front door. But for those who don't, a treadmill could offer a similar experience, but I suspect the treadmill needs to be a good space (light, airy room, nice outlook from a window).