While not practical for operations which very low processing times and correspondingly high change-over times (both values defined by takt time), it is nevertheless a Lean Manufacturing goal to achieve single piece flow in every operation possible. Achieving one-piece flow requires the elimination of waste.
Throughout human history, most people live and die in the social class into which they were born. If they were born poor, chances are they will die poor. One way societies can help people rise in social class is to initiate new enterprises, like improved educational opportunities or technological advancements.
It drains us, leaves us feeling as bad as before, physically worn out and emotionally depleted, instead of proud of ourselves and invigorated. Other people with depression seem to work very hard all the time, but there is little payoff for their efforts.