Leaving the past behind does not mean you forget about what brought you to this very moment. Instead, it means you accept the past for what it is, your foundation; without it, you would not be where you are today. The good, the bad, the ugly and the complicated, it has all played a small part in your bigger picture. If you fail to acknowledge that, then your past will stunt your growth rather than encourage it.
Only you can decide which step you take, which way you grow, and it's those little decisions which will always bring you to tomorrow's today.