Is exercise a 'good thing'?

Exercise has emerged as a central concern in longevity and good health in the past 25 years, partly due to national pride, partly to business entrepreneurship and partly to scientific fact. There is still little hard evidence that exercise can prevent cardiovascular diseases. Any attempts at sound enquiry into the effects of exercise are hampered by the lack of specific regimens and reliable measuring devices. On the other hand, there is considerable morbidity associated with injudicious exercise activities.