Will your exercise kill you?

Back in my twenty plus years it seemed I had boundless energy. While serving ashore while still in the RN, I was able to ride my 'Claude Butler' Racing Bicycle from Portsmouth to London and beyond and return over a weekend, my best achievement was approx 360 Miles in 76 Hours starting at 4-15 am Fri to 9 am Monday. Nowadays or fifty years later half a dozen trips up and down the stairs a walk in the garden daily plus a weekly canter around the the supermarket keeps me reasonably fit. also I can nearly reach my toes standing. Now I am told extreme exercise is likely to lead to permanently damage the heart and trigger rhythm abnormalities and that the safe upper limit for heart health is one hour a day, after which there is little benefit. Activities such as marathons, Iron man triathlons and very long bicycle races may cause structural changes to the heart and large arteries. So it seems exercise is generally beneficial but could tip the scales when used to excess. How do you achieve your daily exercise particularly so if you are an ardent blogger leading a sedentary lifestyle***. My eight year old swivel seat has an estimated 8,640 hours on its 'Clock or seat'. ***Romping in the boudoir is not a beneficial activity when used to excess. Back soon... Vest.