Contrition is “sorrow of the soul and detestation for the sin committed, together with the resolution not to sin again.” The reception of this sacrament ought to be prepared for by an examination of conscience made in the light of the Word of God. The passages best suited to this can be found in the Ten Commandments, the moral catechesis of the Gospels and the apostolic Letters, such as the Sermon on the Mount and the apostolic teachings.
2. The Confession of Sins.
Confession to a priest is an essential part of the sacrament of Penance: “All mortal sins of which penitents after a diligent self-examination are conscious must be recounted by them in confession, even if they are most secret. . . .”
Without being strictly necessary, confession of everyday faults (venial sins) is nevertheless strongly recommended by the Church. Indeed the regular confession of our venial sins helps us form our conscience, fight against evil tendencies, let ourselves be healed by Christ and progress in the life of the Spirit. By receiving more frequently through this sacrament the gift of the Father’s mercy, we are spurred to be merciful as he is merciful.
Absolution takes away sin, but it does not remedy all the disorders sin has caused. Raised up from sin, the sinner must still recover his full spiritual health by doing something more to make amends for the sin: He must “make satisfaction for” or “expiate” his sins. This satisfaction is also called “penance.”
The penance the confessor imposes must take into account the penitent’s personal situation and must seek his spiritual good. . . . It can consist of prayer, an offering, works of mercy, service of neighbor, voluntary self-denial, sacrifices, and above all the patient acceptance of the cross we must bear.
Catechism of the Catholic Church, 1451, 1454, 1456, 1458, 1459, 1460