The root of "happiness" is "hap"--an odd,ancient little word which means
chance or luck. you can see this meaning in words like "haphazard"
(aimless or determined by chance) or even "happen"(something that occurs
by chance or without planning).A long time ago, a person's luck (good or
bad) used to be referred to as one's "hap"
In a word,the link between happiness and good luck is built right into
our language.