I like this very interesting article - it's from The Independent, written by Natalie Haynes entitled: "Why aren't more people walking?" inter-alia:
There's nothing I like more than a report which reaffirms exactly what I already believe, but with numbers.  And this week, Macmilan Cancer Support and the Ramblers have provided exactly that.  "Walking Works" is the title of their study, which is probably what you can expect when you get ramblers to pay for a research project.  But never mind the potential bias: of course walking works.  Walking is the most fun you can have in sensible shoes, and those are the only kind I like.
According their report, it's also a life-saver, helping us fight off heart disease, various cancers, strokes and type 2 diabetes.  All that from something which also gets you to and from work, or the shops, or the park.  That's another reason to love a walk: unlike most exercise it has a secondary purpose.  It gets you somewhere you need to be anyway, and it saves you from getting travel sick on the bus.
Walking is the best way to learn a city (ideally by day).  It takes very little time to find the back streets which have less traffic and pollution, and if it means you turn up everywhere with slightly mussed hair and pink cheeks: so be it.

I really like the above article.  It reaffirms my believe in indulging in walking, jogging and sometimes in 10 km mass runs which I occasionally participate.  It's my adrenalin rush - to be drenched with sweat after the run.  I do hope more people take to walking or jogging - it's the most fun way of getting healthy.