There is now overwhelming evidence that regular physical activity has important and wide-ranging health benefits. These range from reduced risk of chronic diseases such as heart disease, type 2 diabetes, and some cancers to enhanced function and preservation of function with age. As a member of the geriatric set, I am personally delighted that there is strong emerging evidence that activity delays cognitive decline and is good for brain health as well as having extensive benefits for the rest of the body.

I believe that evidence supports the conclusion that physical inactivity is one of the most important public health problems of the 21st century, and may even be the most important. This is not to deny the relevance of other health issues; and certainly we need to pay much more attention to healthful eating habits, smoking prevention and cessation programmes, and state-of-the art and evidence-based preventive medical care. My overriding concern is that the crucial importance of physical activity is undervalued and underappreciated by many individuals in public health and clinical medicine. Figure …