It occurs to me, if we are talking about human behavior and the impact of this behavior on the environment, that we ought to tell all those super-athletes to knock off all the excess exercise. Look at all of the wasted calories from the Boston Marathon! Clearly some exercise is good, it allows us to stay fit and use our calories efficiently, but excess exercise just burns more calories than we need. More calories takes more energy to provide and more energy means more pollution, more waste, etc., etc.
Now I am not sure how much exercise is optimal for this efficiency/no excess trade off, perhaps there is no such thing as excess exercise, but I am not so sure. Besides, how many pairs of shoes do you think these marathoners burn through in a year? How about a nice walk through the Common?
UPDATE: Drat! Once again I have been scooped.