Krishna does not deny the mind is hard to hold — he agrees, then offers the two patient tools that actually work: practice and letting go.
श्री भगवानुवाच असंशयं महाबाहो मनो दुर्निग्रहं चलं। अभ्यासेन तु कौन्तेय वैराग्येण च गृह्यते।।6.35।।
śhrī bhagavān uvācha asanśhayaṁ mahā-bāho mano durnigrahaṁ chalam abhyāsena tu kaunteya vairāgyeṇa cha gṛihyate
The Blessed Lord said: Without doubt, O mighty-armed, the mind is restless, and difficult to control; but through practice and renunciation, O son of Kunti, it may be governed.
— Swami Swarupananda