It is as old as time.  People have used weight training to keep it going at home for a very long time.  It used to be called a hard days work.  Most men had a very rigorous workout out of doors around the homestead.  The women also had their exercise outdoors as well.  In fact, back in the day, in order to just survive in certain areas, a certain number of hours of physical labor were to be endured every day.  Ah, those were the days when it was all spelled out for you and your family.  Plenty of free time once the chores got done.