Happiness lies in the joy of achievement, in the thrill of creative effort. The human spirit needs to accomplish, to achieve, to triumph to be happy.
Happiness does not come from doing easy work. but from the afterglow of satisfaction that comes after the achievement of a difficult task that demands your best.
Your personal growth itself contains the seed of happiness. You cannot pursue happiness by itself. There is no happiness except in the realization that you have accomplished something.
Happiness thrives in activity. It's a running river, not a stagnant pond.