Regret

The hardest thing to let go of is regret. Regret holds the belief that life could be better today if only something was different from the past. To move forward, accept the past as is and that it can't be changed. Accept the present as is and know that there are many opportunities in life for happiness, and that you hold the wisdom from the past to avoid making the same mistakes again. Your future is as bright as you believe it to be. 
-Doe Zantamata