I dont think there is an age.. I think its more of the condition and mind strength of the person.. My father in law retired from operating a motor grader at 75.. He lived 10 more years.. However I currently work with a 70 year old man who is having some issues, he has crashed the city truck several times in the last few years, one was a total loss. the two, I witnessed, was ,, he smashed the driver side mirror, twice.. to me he is not old, but his mind and vision, is failing.. It is sad to see.. He is a good man.. but he is dangerous behind the wheel of an F-350 dually.. I have also worked with drivers that were well into their 70's and keeping a good pace.. Paul, Maybe the young'n needs you to make his lunch from a can of 'Whoop-ass', and see what and old Bloke can do.. I don't have a better answer than, It is about the person in question, not the age.. Jojo