Health is essential for quality of life.  Given the proclivity for injurious behavior (the prime examples being obesity, tobacco, and recreational drugs) I can only conclude that the rational function of the brain is primarily is social including to the generate reasons for what is inexcusable; and the rest of what we do is quite similar to the actions of our cats and dogs.  I wish that all people would develop a love of philosophy (the term in Greek means love of wisdom).  With such love there would be a commitment to hold beliefs in proportion to the evidence in support there of, and there would be a drive for to live a truly moral life.