O my God, I am deeply sorry for offending Thee, and I despise all my sins not only because of Thy due punishments, but also because they offend Thee, my God, Who art all-good and deserving of all my love. I firmly decide, with Thy grace, to sin no more and to avoid future opportunities to sin.
Table of Prayers
Summary: Catholic Prayer Act Of Contrition
My God, I really apologize for my misdeeds. I have sinned against you, whom I should love above all things, by choosing to do wrong and neglecting to do good. I am determined, with your assistance, to do penance, to sin no more, and to avoid whatever causes me to sin. Jesus Christ, our Saviour, suffered and died for us. Have mercy on me, my God, in his name.
Check: Catholic Prayers Before Meal

OR
O my God, I am sorry for offending you with my transgressions. I know I should love you more than anything else. Help me to do penance, do better, and avoid everything that can lead to sin. Amen.