śhrī bhagavān uvācha
asanśhayaṁ mahā-bāho mano durnigrahaṁ chalam
abhyāsena tu kaunteya vairāgyeṇa cha gṛihyate||35||

Meaning : Sri Krishna said:
O mighty-armed Arjuna, the mind is indeed restless and difficult to control, but it can be controlled by constant practice and detachment.