St. Aloysius Gonzaga is the patron saint of young people and those struggling with purity.
St. Aloysius died young, at the age of 23, and is regarded as the patron saint of all young people.
Furthermore, his example of purity at such a young age remains an inspiration. For this reason he is invoked as a patron saint for those struggling with purity.
Here is a prayer from the Raccolta that asks for St. Aloysius’ intercession for a pure mind and body.
O blessed Aloysius, adorned with angelic virtues, I your most unworthy suppliant recommend specially to you the chastity of my soul and body, praying to you by your angelic purity to plead for me with Jesus Christ the Immaculate Lamb, and His most Holy Mother, Virgin of virgins, that they would vouchsafe to keep me from all grievous sin. Never suffer me to be defiled with any stain of impurity; but when you see me in temptation, or in danger of falling, then remove far from my mind all evil thoughts and unclean desires, and awaken in me the memory of eternity to come, and of Jesus crucified; impress deeply in my heart a sense of the holy fear of God; and kindling in me the fire of Divine love, enable me so to follow your footsteps here on earth, that in heaven I may be made worthy to enjoy with you the vision of our God for ever. Amen.