Forgiveness removes that grudge from inside you. It frees the other person from their error. God rewards your act of forgiveness with His own forgiveness to you - the most valuable gift. There is indescribable release for you and the recipient when forgiveness is granted. It destroys His sacrificial work on the cross.
Forgiveness is something that comes up everyday.
Surely you seek it from others everyday, and when you pray you seek it from God. Grant it as easily to all of those around you as easily as you expect it to be granted to you.