Hayagriva Dasa: I've heard that when Indians perform such arduous tasks, they keep their consciousness focused about six inches above their heads, leaving the body to function by remote control. They're always carrying, pushing, or pulling loads much heavier than themselves. Perhaps such intense physical hardship helps them attain the brahma-bhuta platform of self-realization: "Aham brahmasmi. I am not this body. I am spirit."
"In India, knowledge that 'I'm not this body' belongs to the commonest man in the street," Srila Prabhupada once said. "It's no secret. You don't have to pay some guru to tell you. Everyone knows it."