Part of it has to be just time. I used to walk a fair amount. A few miles a day. But as life became more busy there just wasn't time to walk to the grocery store any more - I go to the grocery store on the way back from somewhere else, because I just don't have an hour and a half to buy groceries any more.
As an aside, is anyone else annoyed by the appearance of the word "crisis" in the title of every damn news story? A crisis implies immediate danger. The lack of walking Americans is not a crisis. Global warming is not a crisis. Peak oil is not a crisis. These things are all problems, to be sure, but problems we have some time to deal with. Let's save the word for situations where it applies.
As an aside, is anyone else annoyed by the appearance of the word "crisis" in the title of every damn news story? A crisis implies immediate danger. The lack of walking Americans is not a crisis. Global warming is not a crisis. Peak oil is not a crisis. These things are all problems, to be sure, but problems we have some time to deal with. Let's save the word for situations where it applies.