87 In such retreats and recollection even one who may have entered in sortem Domini , not by the straight way of a true vocation, but for earthly or less noble motives, will be able to "stir up the grace of God." For he, too, is now indissolubly bound to God and the Church, and so nothing remains for him but to follow the advice of St. Bernard: "If sanctity of life did not precede, let it at least follow . . . for the future make good your ways and ambitions and make holy your ministry." The grace of God, and specifically that grace proper to the sacrament of Holy Orders, will not fail to lend aid, if he sincerely wishes to correct whatever was originally amiss in his purpose or conduct. However it may have come about that he undertook the obligations of the priesthood, the abiding grace of this divine sacrament will not be wanting in power to enable him to fulfill them.
Source: Ad Catholici Sacerdotii (Vatican.va)