I think a lot of the decline in physical fitness for the general public is also due to the devalueing of the human body. You used to be a valuable worker if you were in good shape because you could handle a larger workload and accomplish things much more quickly and easily than someone who was not as fit. With the industrial revolution, all men became equal in the eyes of employers regardless of fitness. Add to that that as corporations have grown, they have gotten better and better at devalueing the individual, investing less and less in their employees and trying to figure out how to get the maximum amount of work out of them while still technically following labor laws. When you work for Wal-Mart you know that they don't care about you. And in the training you are exposed to hours and hours of indoctrination and corporate dogma, basically saying "Ask not what the company can do for you, but what you can do for the company". Sacrificing time and aspects of your life and your self are glorified, whereas putting the company anything but first is demonized. It's no surprise then that particularly in American culture where this has been taken to the biggest extreme, that we have people who are working far more and harder for much less at the expense of their health. Most employers don't respect their employees and actively train them to not respect themselves, so of course they're not going to take good care of themselves.
