At one school where I used to teach, on the last day before summer vacation, one of my homeroom students set off a cherry bomb under his desk. If it had not been the last day, if there had been a couple more weeks of school, I would have caught him doing something good. Then I would have remembered that he was basically a good kid. But because it was the last day, I carried my resentment with me into the summer.
Then a group of us sisters were going on a retreat. At that time our order still had a convent in Harrisburg and so we stopped to see the sisters there. A newly-ordained priest was hearing confessions and we were invited to take advantage of the opportunity to receive the sacrament.
When I told him how I could not let go of my bad feelings against this youngster, he asked "Can you pray for him?" I replied, "Yes, I can pray for him." Then the priest looked at me and said, "Then even though you still feel bad, you have forgiven him."