The psychologists Shane Frederick and George Loewenstein have studied this phenomenon and given it a name: hedonic adaptation.
One key to happiness, then, is to forestall the adaptation process: We need to take steps to prevent ourselves from taking for granted, once we get them, the things we worked so hard to get.
the easiest way for us to gain happiness is to learn how to want the things we already have.
we have it in our power to stop grumbling, to be considerate and frank, to be temperate in manner and speech, and to carry ourselves “with authority.”