Do you need to say the number of times you committed a certain sin since it is your first confession?
You Could Have a spiritual priest or deacon that can talk this over with you. A mortal sin is called “mortal” because it is fatal to the soul. Much of the work for a good celebration of the sacrament takes place prior to arriving at the church, and the same with the sacrament of Reconciliation. An honest, humble, and thorough examination of conscience helps you to prepare for the sacrament.
Many people are afraid or embarrassed to go to confession. A commercial was shown on TV. It was a public service announcement encouraging people to have medical tests that could be life-saving, tests they might put off or skip altogether because the test was… let’s say…embarrassing. The key phrase, I will like you to keep in mind is, “Don’t Die of Embarrassment.” The same is true for the health of your soul. And just like I said, mortal sin is called “mortal” because it is fatal to the soul.
It is natural to feel that way but does not let this feeling of shame deter you! Once you have gone through with it for a few times, You will begin to feel more confident and at ease going in.
Now, back to the point. Of course, you are not going to be able to count up 20 years of sin. Unless you keep a very accurate diary. We get that. You’re just going to have to go with trying to be sorry for being unreconciled for so long. And that’s fine.
You may be aware of some ‘challenging areas’ of your spiritual growth and you might need to focus on those. That’s the part you may want to discuss ahead of time with someone.
Also, notice that the name of this Sacrament was changed too. Instead of “Confession”, which is a perfectly fine name, we now call it “Reconciliation” which is an even better name for what is going to take place. Keep that in mind, and everything would turn out wonderfully.
Take note that God has already forgiven you. You should recognize that the person most benefiting from this sacrament is not the priest or Jesus, but yourself. Therefore, Reconciling is now up to you.