Happiness (or contentment) not only needs to be achieved but also maintained. It is not enough to sit back and think things will stay the way they are. The very nature of life is flux. It is ever-changing; an open system requiring a constant flow of energy to maintain its equilibrium. Maintaining contentment is no different.
Perhaps the hardest task of all is the attainment of a level of contentment with which one can be happy. Once achieved, however, continual effort is still required to prevent the contentment from dissipating. A closed system (one with no flow of energy through it) tends towards chaos. Entropy increases with time and, with no additional input, any order which existed is eventually lost.
I have always thought that, by definition, happiness requires no real effort, especially once it has been found, but now, as I write, it sounds suspicious when people say they have ‘found’ happiness. I need to talk this one through with Karaj but it seems to me that if I have worked for my smile then I know what to do to keep it, whereas if I have simply found it then I could just as easily lose it.