St. Aloysius Gonzaga was a pure and innocent soul, always close to God during his short life on earth.
According to Fr. John Croiset in his 19th-century book Devotion to the Sacred Heart of Jesus, Gonzaga had a deep devotion to the Eucharist.
[T]he sublime degree of glory to which he is raised can be nothing but the reward of great merit; and this great merit can only be the fruit of extreme purity of heart, an interior life, living continually in the presence of God, a most tender and ardent love of Jesus Christ -- in fine, of a consummate perfection, which he acquired in a few years by the excessive love and tender devotion which he always had towards Jesus Christ in the most Blessed Sacrament.
This faith was on display most especially during Mass.
[H]e received, from his childhood, the grace of most sublime contemplation and a continual gift of tears. So abundant were these tears especially at Mass immediately after the Consecration, that his garments were all wet with them.
He knew, not only with his mind, but most importantly with his heart, that Jesus is truly present in the Most Blessed Sacrament. This reality moved his heart so much that he cried with joy.