Great forgiveness is not passively forgetting your pain over the passage of time, but actively surrendering it while it still burns bright. Obviously, forgiving over time after the pain has died down is better than not forgiving at all, but it is only a step towards greater, more active forgiveness.
Jesus gave an incredible standard for forgiveness when he declared, “Father, forgive them, for they know not what they do.” He was not only forgiving those who tortured and killed him, but he was doing it in the very moment that they were carrying out that torture and execution, not after he was resurrected and impervious to their pain. Perhaps we will never get all the way to being able to match such great forgiveness as that, but that is the ideal that we are meant to move in the direction of.
Great forgiveness is not passive, it is active.