Could it be because they exercised in a natural way; by way of manual labor? In various forms such as car wash, house cleaning, walking, gardening and such. My

Could it be because they exercised in a natural way; by way of manual labor? In various forms such as car wash, house cleaning, walking, gardening and such. My conjecture is that the rise of exercise/gym coincides with the rise of automated labor and as jobs moved from being labor intensive to knowledge intensive (i.e., as economy moved from agriculture oriented to manufacturing and then finally to service oriented).