Do not be anxious about anything, but in everything by prayer and supplication with thanksgiving let your requests be made known to God. And the peace of God, which surpasses all understanding, will guard your hearts and your minds in Christ Jesus.
One of the reasons this passage is so popular is its simplicity. The opposite of anxiety is peace. Anxiety is forbidden; peace is commended. It is God’s own version of “Don’t worry, be happy” — but with a glorious twist deeper than the universe, as John Piper explains in this three-minute video.