“Unless one is able to fix the mind at the lotus feet of the Lord, the mind is impossible to control. As Arjuna says in Bhagavad-gita (6.34):
cancalam hi manah Krishna pramathi balavad drdham
tasyaham nigraham manye vayor iva suduskaram
“For the mind is restless, turbulent, obstinate and very strong, O Krishna, and to subdue it, it seems to me, is more difficult than controlling the wind.” The only bona fide process for controlling the mind is to fix the mind by service to the Lord. We create enemies and friends according to the dictation of the mind, but actually there are no enemies and friends. panditah sama-darsinah. Samah sarvesu bhutesu madbhaktim labhate param. To understand this is the preliminary condition for entering into the kingdom of devotional service.
Source: A.C. Bhaktivedanta Swami Prabhupada (2014 edition), “Srimad Bhagavatam”, Seventh Canto, Chapter 08 – Text 09