I heard it on the radio - I can't remember if it was a commercial or a Public Service Announcement.
It stated that for every hour you walk, you increase your life by one hour.
I don't know how much studying or research went into it - they didn't get into any of the details.
I guess if anyone needed any motivation to get them started, this just might do it.
And that could be all the commercial was trying to do anyway whether it is true or not.