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; 2 Corinthians 10:5 KJV
Thoughts are “cast down” and silenced by speaking the Word of God.
Your racing mind can be reigned in with the bridle of your spoken words. The most effective words are the words of scripture spoken in faith believing.
Memorize verses and rehearse them over and over and find yourself with the well disciplined mind the Bible promises.
For God hath not given us the spirit of fear; but of power, and of love, and of a sound [well disciplined] mind. 2 Timothy 1:7 KJV