The language of commerce has been engineered to describe the overt purpose of a thing, but cannot encompass fringe benefits or peripheral pleasures. It weighs the obvious against what in its terms are incomprehensible. When I drive from here to there, speed, privacy, control, and safety are easy to claim. When I walk, what happens is more vague, more ambiguous-and in many circumstances much richer. I am out in the world. It's exercise, though not so quantifiably as on a treadmill in a gym with a digital readout.