Bhagavad Gita: Chapter 18, Verse 33

धृत्या यया धारयते मन:प्राणेन्द्रियक्रिया: |
योगेनाव्यभिचारिण्या धृति: सा पार्थ सात्त्विकी || 33||

dhṛityā yayā dhārayate manaḥ-prāṇendriya-kriyāḥ
yogenāvyabhichāriṇyā dhṛitiḥ sā pārtha sāttvikī

dhṛityā—by determining; yayā—which; dhārayate—sustains; manaḥ—of the mind; prāṇa—life-airs; indriya—senses; kriyāḥ—activities; yogena—through Yog; avyabhichāriṇyā—with steadfastness; dhṛitiḥ—determination; sā—that; pārtha—Arjun, the son of Pritha; sāttvikī—in the mode of goodness

dhritya yaya dharayate manah-pranendriya-kriyah
yogenavyabhicharinya dhritih sa partha sattviki

Translation

BG 18.33: The steadfast willpower that is developed through Yog, and which sustains the activities of the mind, the life-airs, and the senses, O Parth, is said to be determination in the mode of goodness.

Commentary

Dhṛiti (determination) is the inner strength of our mind and intellect to persevere on our path despite difficulties and obstacles. Dhṛiti is what keeps our vision focused toward the goal, and mobilizes the latent powers of the body, mind, and intellect to overcome apparently insurmountable impasses on the journey.

Shree Krishna now moves on to describe the three kinds of determination. Through the practice of Yog, the mind becomes disciplined and develops the capacity to rule over the senses and the body. The steadfast willpower that develops when one learns to subdue the senses, discipline the life-airs, and control the mind is sāttvic dhṛiti (determination in the mode of goodness).