Thou wilt keep him in perfect peace, whose mind is stayed on thee: because he trusteth in thee. Isaiah 26:3 KJV
Real peace is only found in the Prince of Peace (Jesus). He, and He only, is able to give us supernatural peace that passes all understanding.
So many, today, have been taught that their emotions should control them; that they should be led by their feelings. The truth is that people were created to be led by the Spirit of God and self controlled by faith in the Word of God.
Peace I leave with you, my peace I give unto you: not as the world giveth, give I unto you. Let not your heart be troubled, neither let it be afraid. John 14:27 KJV
For as many as are led by the Spirit of God, they are the sons of God. For ye have not received the spirit of bondage again to fear; but ye have received the Spirit of adoption, whereby we cry, Abba, Father.
Romans 8:14-15 KJV