Because happiness isn't a mental skill. What makes you happy is try to have and keep peace with everyone and do good things, make presents to others, give and don't expect to get something back (you will but don't expect it). (it's the opposite you see nowadays in movies or series ;-)
It's about social connections and inter-human things ... not some skills you learn on universities but from loving and well raised parents.
>What makes you happy is try to have and keep peace with everyone and do good things, make presents to others, give and don't expect to get something back
Some worse-if-wiser part of me suspects this piece of advice is given out of altruism to the community as a whole, not the person receiving it. Doing this has never made me happy. I'm more willing to do it when I'm already happy though, so maybe there's a corellation.
It's about social connections and inter-human things ... not some skills you learn on universities but from loving and well raised parents.