One of the greatest blessings and purposes for Jesus' Atonement is repentance. Over and over again, I am grateful that I can seek forgiveness for shortcomings and actually be forgiven. True, those wronged may hold a grudge and never forgive, but I know that my Redeemer lives and forgives.
Matthew 6:12 To be forgiven, however, I must first forgive others. Matthew 6:13-14 Because it is sometimes hard to let go of hurts, this is a difficult step. Since I understand this about myself, I can be more understanding of those who won't forgive me. Nevertheless, I've found it easier to give away the burden of guilt and anguish that stick around until I repent of wrong doing as well as bitterness and anger of grudges. Since I prefer the relief, joy, and comfort that forgiving and forgiveness brings, it's a mystery why I sometimes justify a grudge by saying 'I'm not ready to let go of that yet.' It's pretty silly; besides most offenses are unintentional. Jesus even counseled us on injuries that are indeed intentional. Matthew 5:44; Luke 23:34 If Jesus can remember my sins no more, I should give the same benefit to others. Just as poison can kill the body, grudges can surely poison the soul. Doctrine and Covenants 58:42; Isaiah 1:18
If it is difficult, praying for God's grace and strength to overcome a grudge is always helpful. Finally, the sin of not forgiving is the greater sin. Doctrine and Covenants 64:9-10
Heavenly Father and Jesus Christ teach the message all through the scriptures that the commandments will make me happy. Accepting the miracle of repentance, I can have rest from the burdens and cares of this world. Matthew 11:28-30 Even though some see striving to live like Jesus a terrible bore and burden, I know it is lighter and happier. 3 Nephi 9:13-14
"Many...don't understand what repentance really is. Repentance is more than just undoing the wrongs you've done. It's a whole change of your outlook on life. You want to think like the Lord. You want to talk like the Lord. You want to act like the Lord. You want to believe, you want to pray, you want to love the way the Lord does. And then you're converted."—Russell M. Nelson, Ensign and Liahona, June 2005