I grew up in NYC, where public transport was the norm. My dear grandmother, as obese as she was, labored up and down the subway stairs in one of the deepest stations in Manhattan (East Broadway) going to work – I think it was a good thing for her! Some have said that NYC residents are some of the most fit in the US, given low car ownership. I myself gained 30 lbs in just a few months after buying my first car; I had stopped walking the hills to and from UVa Hospital in Charlottesville VA, where I was an intern.
Here in Chicago, I am blessed have 4 or 5 bus lines at my doorstep, and a commuter train 2 blocks away. I do have a car (in the shop right now), but I also avail myself of the bus and train. New software tracks buses by GPS (on computer or cell phone) so you don’t have to freeze on the corner so long!