Everyone has their own standard of happiness. Maybe today that makes him happy is when he can complete the task faster than usual. But on another occasion, happiness can be gained while getting new challenges that promise better achievement.
Far on the other side, those who live modestly feel greatly happy when they get a plate of rice and a side dish, though there is no guarantee tomorrow can get a decent meal.
Happy is not just a certain person. Happiness is everywhere because it belongs to everyone.