Absolutely nothing on abilities when younger but if based on current abilities being a 71yo geezer with arthritis and cancer I would also say BICYCLING. Yesterday's 101 miles was done for a bicycling friend's 9th anniversary of his being hit and killed by a semi shortly after beginning the last week's worth of bicycling to Key West, FL that began in Prudhoe Bay, AK. I completed only 115 of the desired 143 miles for my 7/10 Birthday Ride and was disappointed because my goal was to double my age and add 1 mile as I have done for years. Really can't complain because for my 4th of July ride 6 day's earlier I crashed at mile 100 and managed to cause a slight Rotator Cuff tear.