Philippians 4:6-7

Be careful for nothing; but in every thing by prayer and supplication with thanksgiving let your requests be made known unto God. And the peace of God, which passeth all understanding, shall keep your hearts and minds through Christ Jesus.

King James Version

Paul wrote these lines from a prison cell. He invites you to bring every worry to God, with thanks for what is still good. Peace from God then stands guard over your heart and mind.