Joy is thankfulness, and when we are joyful, that is the best expression of thanks we can offer the Lord, Who delivers us from sorrow and sin.
We need repentance. You see, repentance is not only going to a priest and confessing. We must free ourselves from the obsession of thoughts. We fall many times during our life, and it is absolutely necessary to reveal everything [in Confession] to a priest who is a witness to our repentance. Repentance is the renewal of life. This means we must free ourselves from all our negative traits and turn toward absolute good. No sin is unforgivable except the sin of unrepentance.