This is a Catholic thing. The Catholic Church is big on repentance. The "How to Confess" node gives an overview.
There are many versions of this in English, but this one appeals to me (largely because it's got that nice ominous bit about "the pains of Hell", as my esteemed colleague observes):
O my God, I am heartily sorry for having offended Thee.
I detest all my sins because I dread the loss of Heaven and the pains of Hell, but most of all because they offend Thee, my God, Who art all-good and deserving of all my love.
I firmly resolve, with the help of Thy grace, to confess my sins, to do penance, and to amend my life. Amen.1
This is good solid Catholicism here: We feel bad. We're scared of God, but more importantly, we love the old guy. We regret our sins not because we got caught, but because what we did was wrong and because it displeased God. We intend to keep on feeling bad, and to get it right next time.
You can rattle this off without giving it much thought, but if so, you might as well be reciting Led Zeppelin lyrics for all the good it'll do your immortal soul. Your intent is what matters. The ritual is designed to get your mind focused on God, Last Things, damnation, and whatnot. That focus should help you get your intent on the right track, but the ritual itself is not the active principle here.
Somebody (I've forgotten who, for which I'm heartily sorry) reminded me that the "pains of hell" part has been replaced in recent years with something milder. Vatican II, or some later outrage? I know not, but It's a damn shame. We've got our niche, dammit, let's make the most of it and let the Episcopalians occupy theirs in peace.
I'm kinda apostate and long out of practice. If I've gotten anything wrong, I'd be grateful for corrections or suggestions from real dues-paying Catholics.
1
From the
Small Catechism of the Catholic Religion by
Bishop John Neumann of the
Congregation of the Most (
not merely the second most)
Holy Redeemer, Fourth
Bishop of
Philadelphia,
1884.