Yes this quote gives us very simple and practical solution on how to lead a happy life. Forgiving and forgetting is the way to a happy life.
It is not easy. But if we just cling to any wrongs done to us by others and keep on thinking about them, it will only affect us. We build hatred towards those who have done such a thing. As we keep on dwelling, reminding ourselves about the past, the hatred will grow into a vengeful attitude. May be one day we may take revenge. But all this will make us frustrated, obsessed, stressed out. Ultimately these feelings create tension and unhappiness. It is also a waste of time. We can use this time of hating others for our progress, peace and happiness.
Instead if we forget and forgive, there ends the matter.We will lead a happy life and march forward. That is why all the religions stress on Forgiving and Forgetting.