The mind is very restless, turbulent, strong and obstinate, O Krishna. It appears to me that it is more difficult to control than the wind
Arjuna, Bhagavad Gita (6.34)
Lord Krishna said: O mighty-armed son of Kunti, what you say is correct; the mind is indeed very difficult to restrain. But by practice and detachment, it can be controlled
Bhagavad Gita (6.35)