There are prayers and literary passages that help one retain control in the face of stress. The 23rd Psalms and the Lord's Prayer are good religious choices. I also like the Litany Against Fear from Dune and a variety of poetry. Controled fear is a powerful ally. It brings on adrenalin, crystalizes the thoughts and prepares you for fight or flight.
Uncontroled fear becomes panic.
Panic is your worst enemy.