The mind cannot order the heart to stop desiring those things that the mind considers inappropriate, but it can prevent the heart from developing those desires.
Man's innate controls allow him to avoid the development of feelings and urges that run counter to his awareness.
There are limits, however, to this mental sovereignty.
And if a person allows himself to cultivate such feelings beyond a certain limit, the mind will lose control.
The monster that he himself creates and nurtures will accept little authority.
Yet as long as one is levelheaded, he has the possibility of being master of his heart, mouth, and actions.
Mouths cannot speak of their own accord-only from the, desire to speak.
Nor can other limbs act automatically, without a person's conscious will and awareness.
–Rabbi Adin Steinsaltz
From Opening the Tanya by Rabbi Adin Steinsaltz