In most countries throughout the world, except those affected by the HIV-Aids epidemic, populations are increasing in size, rapidly getting older, and becoming more sedentary. This combination, along with the adoption of unhealthy habits such as cigarette smoking and consumption of an animal-based rather than a plant-based diet, will result in chronic degenerative diseases becoming the most common cause of disability and premature death throughout the world during the first twenty-five years of this new millennium. As more and more populations acquire the technology that reduces the need to exercise for transportation, occupation or maintaining a household, lack of activity quickly becomes a major risk for coronary heart disease, stroke, hypertension and noninsulin dependent diabetes mellitus. This lack of activity appears to contribute to other disorders such as osteoporosis and selected site-specific cancers. In older persons, inactivity can become a major reason for loss of physical independence and a reduction in their quality of life. Public health approaches will be needed to reverse this trend of increasing "hypokinetic" diseases as the computer/communication revolution becomes worldwide. These public health programs will need to be supported by government and corporate changes in policies that provide time, facilities and incentives for maintaining an appropriately active life-style. The goal should be for all adults to perform at least 30 minutes of moderate to vigorous intensity exercise on most days.