Bg 2.60

yatato hy api kaunteya
purusasya vipascitah
indriyani pramathini
haranti prasabham manah

Word for word: 
yatatah — while endeavoring; hi — certainly; api — in spite of; kaunteya — O son of Kunti; purusasya — of a man; vipascitah — full of discriminating knowledge; indriyani — the senses; pramathini — agitating; haranti — throw; prasabham — by force; manah — the mind.

Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
The senses are so strong and impetuous, O Arjuna, that they forcibly carry away the mind even of a man of discrimination who is endeavoring to control them.

Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
There are many learned sages, philosophers and transcendentalists who try to conquer the senses, but in spite of their endeavors, even the greatest of them sometimes fall victim to material sense enjoyment due to the agitated mind. Even Visvamitra, a great sage and perfect yogi, was misled by Menaka into sex enjoyment, although the yogi was endeavoring for sense control with severe types of penance and yoga practice. And, of course, there are so many similar instances in the history of the world. Therefore, it is very difficult to control the mind and senses without being fully Krishna conscious. Without engaging the mind in Krishna, one cannot cease such material engagements. A practical example is given by Sri Yamunacarya, a great saint and devotee, who says:

yad-avadhi mama cetah Krishna-padaravinde
nava-nava-rasa-dhamany udyatam rantum asit
tad-avadhi bata nari-sangame smaryamane
bhavati mukha-vikarah susthu nisthivanam ca

“Since my mind has been engaged in the service of the lotus feet of Lord Krishna, and I have been enjoying an ever new transcendental humor, whenever I think of sex life with a woman, my face at once turns from it, and I spit at the thought.”

Krishna consciousness is such a transcendentally nice thing that automatically material enjoyment becomes distasteful. It is as if a hungry man had satisfied his hunger by a sufficient quantity of nutritious eatables. Maharaja Ambarisa also conquered a great yogi, Durvasa Muni, simply because his mind was engaged in Krishna consciousness (sa vai manah Krishna-padaravindayor vacamsi vaikuntha-gunanuvarnane).