In 1994, Professor Jeremy Morris, speaking at a symposium honoring Dr. Ralph Paffenbarger’s 70th birthday, proclaimed physical activity as the “Best Buy in Public Health.”1 Morris and Paffenbarger are the founding fathers of physical activity as a public health issue because of their seminal epidemiologic research in the 20th century. Today, more than 20 years later, bargain-hunting American consumers who usually buy anything “on sale,” aren’t buying. For more than 20 years, the estimated proportion of Americans meeting the recommended volume for weekly physical activity has been stable. Little or no change has occurred except when the measurement device or the definition of recommended activity has changed. Americans today are less active than Americans 50 years ago because the volume of