Bhagavad Gita 18.33

धृत्या यया धारयते मन:प्राणेन्द्रिय:क्रिया: |
योगेनाव्यभिचारिण्या धृति: सा पार्थ सात्त्विकी

Translation

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.