That’s a great start! Tell me, who assigns you the penance you need to do?
After King David committed adultery with Bathsheba, he later came to realize his error and was very sorry. God forgave him, but there was still a penalty for his sin. David’s little baby boy did not live.
That’s why Jesus instituted the sacrament of penance to be given by a Priest. In Matthew 18:15-18, Jesus gives his representative, the Priest, the power to hear a confession and forgive sins. The Priest then assigns us penance, usually in the form of prayer. When we cooperate with the healing spiritual remedy that God has given us, not only are we saved from punishment after death, but we are also protected, to some degree, from the consequences of our sins in this life.
Another good scripture is Ezechiel 18:21-23