‘Obligatory act’ is that which is appropriate to one’s own station and stage of life. Doing it ‘without attachment’ means devoid of attachment to agency etc., and ‘without desire or aversion’ means that it is not done through desire to win fame and aversion to win notoriety, i.e., is performed without ostentation—when obligatory works are performed in the above-mentioned way by one who is not after their fruits, they are said to be Sattvika.