Catechism of the Catholic Church

Fortitude is the moral virtue that ensures firmness in difficulties and constancy in the pursuit of the good. It strengthens the resolve to resist temptations and to overcome obstacles in the moral life. The virtue of fortitude enables one to conquer fear, even fear of death, and to face trials and persecutions. It disposes one even to renounce and sacrifice his life in defense of a just cause. "The Lord is my strength and my song." "In the world you have tribulation; but be of good cheer, I have overcome the world." (2848, 2473)