The Act of Contrition is usually associated with the Sacrament of Confession, but Catholics should also pray it every day as part of their normal prayer life. In it, we acknowledge our sins, ask God for forgiveness, and express our desire to repent.
The 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 I love 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."