I'm a Canuck...I'm going to a retirement dinner on Friday for a fellow that is 60 and has done 43 years in the army. His 2 clasps on his CD say it all and his last BFT of 13 km was only 3 mins slower than the youngster that finished first.
When I did my basic, we had a fellow on course that was 46 (that's when we could stay in until 55). The fellow put us to shame while at the same time highly motivating us to keep up with him for fear of being labelled the one the old guy beat.
There are some right gnarly old sods about.
A Polish guy who swims at my local pool is an ex Olympian.
He still swims butterfly, runs three miles a day, at a respectable pace and coaches tennis.