Old people's physical strength was too much

I don't know if this is considered everyday life, but this is a story about my great-grandmother who passed away at over 100 years old. When she was young (around the time her children were adults), she would walk about 6km to her fields almost every day. On her way back, she'd haul her harvest home on a cart. Sometimes, her children would even ride on the cart. Also, the elevation difference between the fields and her house is about 200m, so it was all downhill going there and all uphill coming back. I just think their stamina and leg strength were too different from ours, making them incredibly strong by modern standards.