A lot of it is stamina. Both physical and mental. Rural peasants are really tough in a way that is extremely foreign to suburbanites. My godfather (indigenous

A lot of it is stamina. Both physical and mental. Rural peasants are really tough in a way that is extremely foreign to suburbanites. My godfather (indigenous peasant in rural Mexico) spent some time in his youth carrying two 50-pound bottles of liquor on his back all day long up and down mountains over a rough trail. I get winded if I try to carry one of those bottles for a block of flat sidewalk. If someone asked me to strap two to a tumpline and hike up a mountain I would call them crazy. He spent other years working on coffee plantations under thieving brutal racist owners. And continued working on his own small plots of land every day up to maybe age 70, even as his body was thoroughly worn out. Now his grandchildren are white-collar professionals. This kind of hard manual labor is as demanding as any high-level sport. It takes years of (mental and physical) training to be able to handle it without falling apart.