Well, to be honest, I am kind of embarrassed when I tell people that I go walking for exercise. "What, you are so out of shape you can't jog? You think walking is going to get you in shape? What's your problem?"
Well, I can jog, I assure you, at least for short distances. But, my goal is to burn fat, not carbohydrates, and I want to keep within my target heart rate, already discussed. I find that a brisk walk, about 4 MPH, up and down hills, does a good job of achieving that target heart rate and staying within it.
The nice thing about walking, is that you can do it anywhere, and you can do it early in the morning, in your own neighborhood, and enjoy the sunrise, or sunset, or listen to music on your headphones. I found a nice walking route around my house that is about 1.5 miles (short version) and 2.8 miles (long version). I found this web site useful for plotting a path, especially using the satellite view at maximum zoom: www.gmap-pedometer.com
There is a web site dedicated to walking, here: www.TheWalkingSite.com