असंशयं महाबाहो मनो दुर्निग्रहं चलं।अभ्यासेन तु कौन्तेय वैराग्येण च गृह्यते॥
asanśayaṃ mahā-bāho mano durnigrahaṃ calamabhyāsena tu kaunteya vairāgyeṇa ca gṛhyate
Word by word
The verse says
Krishna said: Without doubt, mighty-armed one, the mind is hard to hold and it is restless. But by repeated practice, Arjuna, and by dispassion, it is held.
In plain words
Krishna agrees with him. That is the first thing to notice.
Asaṁśayam — without doubt, no argument. The objection is granted in full.
And then two words as the answer: abhyāsa and vairāgya.
Where you've felt this · in sport
Your coach watches you fail the drill for the fifth time and says, yes, it is hard. He does not tell you it will come soon. He says do it again tomorrow.
Going deeper
The concession is the remarkable part, and it should not be read past on the way to the answer.
Krishna does not say Arjuna is exaggerating, or that it only seems hard, or that he would find it easier with the right attitude. Asaṁśayam — without doubt. The mind is hard to hold. The wind image stands.
That matters for every reader who has failed at this. The difficulty you have run into is the difficulty the book describes, and it is not evidence that you were doing it wrong.
Then abhyāsa — repeated practice, literally a sitting-down-toward — and vairāgya, the fading of colour, dispassion. Two words, no elaboration, no timescale.
And they work together in a way that neither does alone. Practice without any cooling of appetite is a person rowing against their own current. Dispassion without practice is an opinion. What is offered is not a technique so much as a direction and a very long time.