Ensign, Nov. 2009 pg. 46; “When temptation comes, you can invent a delete key in your mind—perhaps the words from a favorite hymn. Your mind is in charge; your body is the instrument of your mind. When some unworthy thought pushes into your mind, replace it with your delete key. Worthy music is powerful and can help you control your thoughts (see D&C 25:12).” – Boyd Packer
2 Cor. 10:5; “Casting down imaginations, and every high thing that exalteth itself against the knowledge of God, and bringing into captivity every thought to the obedience of Christ.”
Note: It’s not bad to fill your thoughts with a hymn when encountering spiritual warfare in your mind, but why is it the Mormons don’t think of using biblical scripture? And who is determining what is worthy?