From my experience, there are around 200 Bible verses worth memorizing for quick access in any situation throughout the day, every day. One of these is a familiar verse that you likely already know - Philippians 4:6-7.
"Do not be anxious about anything, but in everything by prayer and petition, with thanksgiving, present your requests to God. And the peace of God, which transcends all understanding, will guard your hearts and minds in Jesus."