Yep, the great American myth of the superhuman farm boy - definitely Beverly Hillbillies / Andy Griffith / Green Acres material.
Having grown up in a farming community, I will say this though... I remember about 20 years ago, my parents' generation back in my hometown complaining about how their kids, who either went to college and got office jobs or used gasoline powered machines to do all the jobs that used to be done by hand, had become soft and fat. I was back there this summer and I'd swear half the town should've had "Goodyear" painted on their sides.
There were a lot of Amish and Mennonite dairy farms where I grew up. The guys who milked cows by hand were some of the best wrestlers in school - they had grips of steel.