It is said?
Amount of calories burnt walking depends on factors?
So it would follow that you could burn that much calories, which we're not exactly sure of, in less than a football field length?
Football field is 120 yards, end zones count.
I'm just saying that the notion of using a football field is misleading since not everyone is around a football field everyday. City blocks are a much better comparison.
http://goo.gl/maps/Lndyv
http://goo.gl/maps/z3lqu
There goes what a football field looks like in terms of an actual city environment. Walking 2 short blocks is no arduous task.