During the performance of an action, a performer is carrying a particular conviction that determines the quality of action. Krishna describes how a conviction can belong to three modes depending on one’s consciousness behind the action.

The conviction (dhṛtyā), by which (yayā) the activities of the mind, life, and senses (manaḥ-prāṇendriya-kriyāḥ) are sustained (dhārayate) by undeviating (āvyabhicāriṇyā) practice of yoga (yogena), that conviction (dhṛtiḥ sā) is in the mode of goodness (sāttvikī). (BG 18.33)

But (tu) that conviction (dhṛtyā), which is eager for fruit (phalākāṅkṣī), by which (yayā) righteousness (dharma) is sustained (dhārayate) for the sake of (arthān) enjoying lustful desire (kāma) with intense attachment (prasaṅgena), that (sā) conviction (dhṛtiḥ) is in the mode of passion (rājasī). (BG 18.34)

The unintelligent (durmedhā) conviction (yayā) by which one cannot give up (na vimuñcati ) sleep (svapnaṁ), fearfulness (bhayaṁ), lamentation (śokaṁ), depression (viṣādaṁ) and even madness (madam eva ca), that (sā) conviction (dhṛtiḥ) is in the mode of darkness (tāmasī). (BG 18.35)