The comments about exercise being harmful would have had my full support until recently. I recall a jogger who ran into a chain fence one early morning, bursting his spleen and causing his demise......Indeed much of the rubbish about its benefits comes from some dubious work in the US which was never questioned.
However, recently there has been some interesting research which shows that regular exercise can reduce the amount of fat in your blood and reduce diabetes. It also increases muscle mass which has been suggested may reduce the risk of death within three months of major surgery such as operations for bowel cancer or fractured hips. We also know that progressive exercise after heart attacks increases life expectancy.
I wouldnt start to suggest this is proof that exercise will make you live longer if you are otherwise well, but these isolated findings and associations are starting to come together to make a resounding case for regular safe exercise.