Writing about St. Vincent de Paul’s formation of the early Daughters of Charity:

“Besides the intellectual and medical training, St. Vincent insisted also on the moral training of his recruits. The purpose of this training was self-sanctification and at the same time character formation. It was to teach the novices to rise superior to petty differences and jealousies, to bear up under trials and disappointments, and to render them selves immune to the moral dangers connected with their work. Hence we find that St. Vincent laid great emphasis on mutual charity and forbearance, on humility, obedience to the rules of the Company, and detachment from earthly goods and honors. These virtues served as an antidote to jealousy and envy while assuring unity among the members… Patience and trust in God upheld their courage in the face of disappointments… In all these virtues did St. Vincent endeavor to ground his first Daughters of Charity, as a glance at his conferences to them amply shows.”
(The Charities of St. Vincent de Paul: An Evaluation of His Ideas, Principles and Methods by Cyprian William Emanuel, O.F.M., p. 144)

In this video Saint Vincent explains the virtues of mortification and humility, and how suffering can be turned into opportunities.