You may already have your favorite prayer or perhaps a Bible verse you use.

A prayer that Unity students have been using for a very long time is
"The Prayer of Faith" by Hannah More Kohaus:

God is my help in every need;
God does my every hunger feed;
God walks beside me, guides my way
Through every moment of the day.

I now am wise, I now am true,
Patient, kind , and loving too.
All things I am, can do, and be
Through Christ, the Truth that is in me.

God is my health, I can't be sick;
God is my strength, unfailing, quick;
God is my all; I know no fear,
Since God and love and Truth are here.

You can use these words, especially "God is my help in every need" to
calm yourself during a stressful situation. Saying "God is my help" and
taking this realization into your heart will give you such a sense of peace.

Others have found comfort in the words of Unity's

Prayer for Protection

The light of God surrounds me;

The love of God enfolds me;

The power of God protects me;

The presence of God watches over me.

Wherever I am, God is!

taken from A Gift from your friends in the Silent Unity Prayer Ministry booklet "Peace"