The best way to control our thoughts is to offer the mind to God in complete surrender. The Holy Spirit will accept it and take control of it immediately. Then it will be relatively easy to think on spiritual things, especially if we train our thought by long periods of daily prayer. Long practice in the art of mental prayer (that is, talking to God inwardly as we work or travel) will help to form the habit of holy thought.
—The Best of A. W. Tozer: Volume 1, 45