41 Then, too, what a wonderful, what a heartening spectacle of religious fervor it will be to see the countless armies of Christians throughout the world devoting themselves to assiduous prayer and voluntary self-denial in response to Our appeals! This is the sort of religious fervor with which the Church's sons and daughters should be imbued. May their example be an inspiration to those who are so immersed in the affairs of this world as to be neglectful of their duties towards God.
Source: Paenitentiam Agere (Vatican.va)