People today live under arguably very "unnatural" circumstances.
Humans didn't evolve living alone in tiny apartments eating out of cheap restaurants and convenience stores, spending the vast majority of their time sitting down indoors. When you live this kind of lifestyle - more or less cut off from social networks and regular physical exertion connected with hunting/gathering - for any length of time, we should expect some kind of nasty physical backlash, and we need methods to counter them.