“Arjuna, a life that does not follow this method of prosperity is a filthy life. Such people live meaninglessly intoxicated by sensual ‘pleasures.’” 
To be happy and healthy as a natural side effect of being responsible and dutiful is right, moral, and good. But to seek happiness and enjoyment independently and for its own sake is ‘filthy’ and superficial.
The Main Purpose of Duty
“Although duty can naturally produce pleasant side effects, such benefits are not the motivation of a spiritual person who is perfectly satisfied by his own being, whose thirst is quenched by his own soul, and who experiences pleasure within himself. Such people are completely independent and have no ulterior motive for performing or not performing any deed. So always try to fulfill your responsibilities without ulterior motive. Working without personal attachment is the means by which human beings become transcendental.” [17-19]