Act of Contrition
O my God, I am heartily sorry for having offended thee, and 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.
Source. Baltimore Catechism (1885). O my God, I am heartily sorry for having offended thee, and 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.
On the wording. several approved forms exist; this is the Baltimore form most Americans memorized. Any sincere act of contrition is valid — the page says so.