Bhagavad Gita 6.36

असंयतात्मना योगो दुष्प्रप इति मे मति: |
वश्यात्मना तु यत्ता शक्योऽवाप्तुमुपयत्:

Translation

Yog is difficult to attain for one whose mind is unbridled. However, those who have learnt to control the mind, and who strive earnestly by proper means, can attain perfection in Yog. This is My opinion.