penance

109. And also, after confession, you must remember the sins you have committed, in order to excite your heart to feelings of shame and sorrow, humbling yourself before God. But do you remember to exercise yourself in this humility? This is a humility of precept. "The whole life of the Christian must be one long penance." [Sess. I, cap. ii] Thus speaks the holy Council of Trent, where the whole Church of Christ was assembled, and its dogmas are infallible not less in matters of morality than in those of faith.
The Council of Trent says "must be," which is a formula not of exhortation but of necessity; and it does not prescribe such penances as scourgings, hair shirts, or fasts, but speaks generally; and we cannot interpret the sense of these words with more discretion than by saying: "If you cannot perform certain exterior penances, you must nevertheless never neglect those interior penances which consist in the contrition and humiliation of the heart, saying with David: 'Have mercy upon me, O God. . . . against Thee only have I sinned. . . . A contrite and a humble heart, O God, Thou wilt not despise.' " [Ps. l] Do you practice this penitential humility? O my God! Your sins are so numerous, and yet you live in absolute forgetfulness of them, as if you were innocent!
Do you remember the obligation you are under to think often: "What have I done? What great evil have I done to offend God?" Pray to God that He may give you light to know the gravity of your sin, and you will have that continual sorrow which King David had, if you can say with him: " I acknowledge my iniquities."