Hmmm, I've known people who focus on their happiness. A strange thing, but not one of them ever found happiness, while in the end they sacrificed anything and everyone who meant anything to them.
To do what you say needs wisdom, and only a fool thinks of himself as wise.
Wisdom, yes! A man needs to be happy. It doesn't have to be a selfish thing. But trading your own happiness for something not 'worth' it would be a mistake because if you are not happy, you 'cannot' be productive!