"...If there be any virtue, and if there be any praise, think on these things" (Philippians 4:8)
The Bible has a great deal to say about our thoughts; current evangelicalism has practically nothing to say about them. The reason the Bible says so much is that our thoughts are so vitally important to us. The reason evangelicalism says so little is that we are overreacting from the "thought" cults, which would make our thoughts to be very nearly everything and we counter by making them nothing. Both positions are wrong.
Our voluntary thoughts not only reveal what we are - they predict what we will become. The will can become the servant of the thoughts, and to a large degree even our emotions follow our thinking. Thinking stirs feeling and feeling triggers action. That is the way we are made and we may as well accept it.
Thinking about God and holy things creates a moral climate favorable to the growth of faith and love and humility and reverence. We cannot by our thinking regenerate our hearts, nor take our sins away nor change the leopard's spots. But we can by Spirit-inspired thinking help to make our minds pure sanctuaries in which God will be pleased to dwell.
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, even talking to God inwardly as we work or travel.
~A. W. Tozer~