Move or Die

Human evolution has lots of inbuilt rules to ensure the survival of the species.  One of them could be called, "use it or lose it," or more coldly, "move or die." 

Once a person is past the mating age, movement is a strong (perhaps the strongest) signal to the body.  If a person quits moving regularly, the body reads this pattern and allows various systems to start to decay.  Yet if a person continues moving on a regular basis, they are still "in the game," and the body will continue with maintenance functions.

This recent study shows just that: that in older people, mortality is inversely related to energy expenditure.  The study points out that it's not really any particular type of activity that's important.  Instead it's the more total energy that is expended, the lower the chance of death. 

Nature gives us some simple laws that we can ignore at our own peril.  To stay healthy, we have to keep moving as much and as long as we can.