You can walk 2 miles in 28 minutes

Anybody can run a mile in 10 or 12 minutes; the more out of shape you are, the more hours you will spend wheezing afterward.  Maintaining a vigorous walking pace for a longer period of time is actually a better measure of your fitness.  According to Swedish researchers, a fit 40 year old man should be able to walk 2 miles in under 30 minutes.  If you can cover that ground in under 28 minutes you are in excellent shape.