Now, sometimes this is misunderstood as a kind of masochism, a desire for pain, but it is no such thing. It is a willingness to bear our sufferings (with the help of God's grace, of course), to take up our cross as Christ did, and to offer reparation for our sins.
Penance requires several things, as the catechism tells us:
"Penance requires . . . the sinner to endure all things willingly, be contrite of heart, confess with the lips, and practice complete humility and fruitful satisfaction." CCC 1450
In this post, I'm mostly focusing on the "fruitful satisfaction" part of penance, because while the other parts of penance are things even many non-Catholics embrace and practice, the satisfaction aspect tends to be something particularly unique to Catholics.
Many non-Catholics have a hard time understanding why we think penance is even necessary. "Didn't Christ finish all the work on the cross?" they ask. And we respond, He did more than just do it for us, He asks us to join our work with His, He sanctifies our work, which without Him could do nothing to save us. What penance is NOT is "earning" our salvation. It's abundantly clear by our actions that we don't deserve it! Yet whenever we ask for forgiveness, it's given to us, thanks be to God. There is still our mess to clean up, though.
A common analogy is one of a boy playing baseball, who hits the ball through a neighbor's window. He goes to the neighbor, apologizes, and the neighbor graciously forgives him. But, the window is still broken. His penance would be the act of perhaps working to get enough money to replace that window.
When we sin, we harm ourselves and possibly others. Penance is working to repair the harm done, it's attempting to clean up our mess.
The catechism continues:
1459 Many sins wrong our neighbor. One must do what is possible in order to repair the harm (e.g., return stolen goods, restore the reputation of someone slandered, pay compensation for injuries). Simple justice requires as much. But sin also injures and weakens the sinner himself, as well as his relationships with God and neighbor. 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."
1460 The penance the confessor imposes must take into account the penitent's personal situation and must seek his spiritual good. It must correspond as far as possible with the gravity and nature of the sins committed. 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. Such penances help configure us to Christ, who alone expiated our sins once for all. They allow us to become co-heirs with the risen Christ, "provided we suffer with him."
The satisfaction that we make for our sins, however, is not so much ours as though it were not done through Jesus Christ. We who can do nothing ourselves, as if just by ourselves, can do all things with the cooperation of "him who strengthens" us. Thus man has nothing of which to boast, but all our boasting is in Christ . . . in whom we make satisfaction by bringing forth "fruits that befit repentance." These fruits have their efficacy from him, by him they are offered to the Father, and through him they are accepted by the Father.
The practice of denying ourselves in a culture obsessed with immediate satisfaction is a truly beneficial spiritual exercise. It reminds us of our weaknesses and our utter dependence upon God, it makes apparent our attachment to earthly trifles.
But even more, Christ's sacrifice has given value to any sacrifice, however small, that we unite with His cross. Catholics have a saying, I've been told one that is heard often from mothers and teaching nuns, which is "Offer it up." The smallest discomfort, the slightest pain, up to the most difficult struggles can be offered up as personal sacrifices, accepted as personal crosses, and joined with Christ's sacrifice which gives it value. We receive grace for accepting our crosses, by the power of Christ's sacrifice we help make reparation for our own sin, and since we are one big family, we can also offer up suffering for the reparation of others as well.
As a simple child, St. Bernadette was told by Our Lady of Lourdes during one of the apparitions to pray to God for sinners. She also said, "Penance, penance, penance." This exhortation to penance is something we recall especially during this season of Lent. We must empty ourselves in order to be filled with Christ's peace and grace. In upcoming posts, we'll look in more detail at some of the specific ways we do that.
Then Jesus said to his disciples, "Whoever wishes to come after me must deny himself, take up his cross, and follow me." (Matt 16:24)
We rejoice in our sufferings, knowing that suffering produces endurance, and endurance produces character, and character produces hope, and hope does not put us to shame, because God’s love has been poured into our hearts through the Holy Spirit who has been given to us. (Rom 5:3-5)
The Spirit itself bears witness with our spirit that we are children of God,
and if children, then heirs, heirs of God and joint heirs with Christ, if only we suffer with him so that we may also be glorified with him. I consider that the sufferings of this present time are as nothing compared with the glory to be revealed for us. (Rom 8:16-18)
But we proclaim Christ crucified, a stumbling block to Jews and foolishness to Gentiles (1 Cor 1:23)
So I ask you not to lose heart over my afflictions for you; this is your glory. (Eph 3:13)
Now I rejoice in my sufferings for your sake, and in my flesh I am filling up what is lacking in the afflictions of Christ on behalf of his body, which is the church, of which I am a minister in accordance with God's stewardship given to me to bring to completion for you the word of God (Col 1:24-5)