Paradoxically, Americans also seem to be some of the quickest to experience disappointment. The article, based on cited studies, suggest that being generally happy leads to the expectation that one will be happy, so even small negative events then cause much grief. In other words, being happy makes one vulnerable to easy disappointment.
Those who have greater struggles tend to find happiness more readily in a way that seems counter-intuitive. The article also suggests ways to get off the happiness cycle - the ups and downs. Which is where the discussion seems to veer closer to our God gives us everything for our enjoyment Sunday admonition from Paul.