The mind can be brought under control through practice and dispassion says the Bhagavad Gita.
Undoubtedly, O mighty-armed one, the mind is difficult to control and is restless; but by practice, O son of Kunti, and by dispassion, it is restrained. (Chapter VI, verse 35)
Dispassion is the giving up of all attachments to the objects of the world and by giving up the expectations for the fruits of action. These two are the main causes for the agitation of thoughts, which thicken the flood of the thought flow and make the mind uncontrollable.
Practice is the constant repetition of an idea regarding one and the same object of thought. From the moment we start trying to become aware of our own lives, we are in the realm of practice. As a result of this, the detachment that comes automatically to us is the true and enduring detachment.
Dispassion born out of practice alone is the charter for spiritual growth.
(Source: Holy Gita – Ready reference – Published by Chinmaya International Foundation, Page 138 - 139)