Well that correlation can work in the other direction too. What if poor US urban planning has led to sedentary lives where walking to places like grocery store

Well that correlation can work in the other direction too. What if poor US urban planning has led to sedentary lives where walking to places like grocery stores, parks, or transit is unpleasant, inconvenient, or impossible. So we sit on our butts and drive our cars everywhere, which means more lanes and more parking lots which in return keeps things farther apart and less walkable. People who are never pedestrians perhaps have reduced empathy for being one, and being in a big metal car vs passing in-person on the street leads to less personable reactions (ie road rage). And car-focused infrastructure decisions lead to more dangerous interactions between fast traffic, pedestrians, and cyclists. The tiny bit of time I have spent in some dense european-style walkable neighborhoods left me feeling much more a part of the neighborhood and like I would be a much healthier person in general living in such a place long term.