Bhagavad Gita 6.33

Arjuna said: I do not see how I can attain this state of equanimity which You have revealed, owing to the restlessness of my mind.

अर्जुन उवाच
योऽयं योगस्त्वया प्रोक्तः साम्येन मधुसूदन।
एतस्याहं न पश्यामि चञ्चलत्वात् स्थितिं स्थिराम्॥

arjuna uvāca
yo'yaṃ yogastvayā proktaḥ sāmyena madhusūdana|
etasyāhaṃ na paśyāmi cañcalatvāt sthitiṃ sthirām||

English translation (above): Shri Purohit Swami (1935), public domain. Sanskrit text via github.com/gita/gita (Unlicense).