Bhagavad Gita 12.9

अथ चित्तं समाधातुं न शक्नोषि मयि स्थिरम् |
अभ्यासयोगेन ततो मामिच्छप्तुं धनञ्जय

Translation

If you are unable to fix your mind steadily on Me, O Arjun, then practice remembering Me with devotion while constantly restraining the mind from worldly affairs.