My grandmother is 90 and other than being a little shrunken, she looks, dresses and acts exactly the way she did when she was 47 (the youngest I remember her and the age I am now). Last year I went out on a quick, fun 10 mile run with some friends, got lost and we ended up running a soggy, cold 15 miles. It was a funny story that I told my mom who in turn shared it with grandma. Grandma had a fit! "Why, you tell her to stop running! She is TOO OLD to run."
Looking back at grandma at this age, I don't doubt she WAS too old to run at 47. But my 47 isn't her 47 or even my mom's 47 - whole different mindset these days and I don't think that is a bad thing at all!
Crap - how did I manage posting 3 times? Must be getting old...