I'm not sure what makes you say that. Did you see many riding mowers in the 60's? Remember how we used to PULL the garage doors open and close. And we had to turn a crank to make our car windows go UP and DOWn - whew.... I'm breaking into a sweat just remembering.
Kids definitely exercised more in the 60's. Since I was a kid back then, I know what I'm talking about. I rode my bike around the neighborhood and over to the tennis courts. There were no video games, so there were more outside games.
People didn't eat out very much in the 60's. If you cook the food yourself you rarely deep fry stuff. It all adds up.