How true this quote is, and in many different contexts, but I choose to use it in reference to healing.
Part of healing and overcoming poor choices of the past is learning to forgive ourselves, letting go and moving on. Yes, there are lessons to be learned and those lessons will change the course of our lives - hopefully in a good way - but each time we look back and rehash, we stunt our growth, which is not what God wants. We can never forget mistakes, but we should also never forget how far we have come.
Overcome the past by looking forward, and be grateful for how far the Lord has brought you.
Always be grateful.