"Whether one is outdoors or on a treadmill, walking improves the generation of novel yet appropriate ideas, and the effect even extends to when people sit down to do their creative work shortly after."

This is actually quite profound. I actually associate walking with the surroundings. It's always pleasant to walk in a forest, or where there is lush greenery. If the surrounding does not matter, then I should stop finding excuses to not walk. An urban environment seems to make no difference.