A walker in the suburbs strolls the streets or ambles through the woods, but her destination is secondary. She walks for the walking and not for where it takes her.
Compare this to a walker in the city, pounding the concrete day after day. Here is walking with purpose, commuting on foot or by subway (which must also be walked to and from); walking to the corner for a newspaper, to the market for a quart of milk. Walking because it's faster than taking a cab. Walking because, well, it's just the way you get around. It is the air you breathe; it is the environment.
All this is to say, a walker in the suburbs forgets how much she walked when she lived in the big city. And when she goes back there her feet remind her. Her soul too. It soars.