How much has your past shaped your present and are you happy with the results?

How much of your thinking today has been shaped by your past? Perhaps your past has been positive and resulted in a positive outlook on life. Or maybe it was mostly negative and has resulted in a negative outlook on life. Perhaps it has been you exceptionally functional or very dysfunctional.

If so could you explain how this has helped or hindered you? If it has been negative how can one change this do you think?