I was a competitive runner for about 7 years, and when I wasn't running I never really felt the need to get out and do much aerobic work or exploration in any capacity. I finished that about a year ago - though I still run a bit recreationally - and I've started going for short walks during the week and long walks (sometimes up to 9 or 10 miles) on Friday evenings after work. It's really amazing how de-stressing it is. Prior to starting this, I thought I had a pretty darn good feel for most of the Twin Cities, but I notice and learn so many more things about neighborhoods going for walks through them.
Although I'm usually listening to podcasts, which the article specifically mentions as a distraction for truly "purposeless walking". Eh.