In life as difficult as it always seems the proper way to live is only in the now. Such existence is void of pain and a lot of suffering, as the Bhudda says "enlightenment is the end of suffering" taking time out to think about it as far as we cannot see the future all our sufferings come from our ties to the past and well our future is full of infinite possibilities so why worry about anything?
This is not just mumbo jumbo it really has been proven, I had my parents seperate at 14 and I always suffered myself over it I'd think about it for long hours and end up crying I was clearly living in the past and suffering and even when time would pass I would remind myself and suffer some more, till I just let go and enlightened myself from all of it and chose to live in Peace both living and being. It all started with some effort to help myself and live in the now which is a way different experience that reaching back into our pain, our minds are .ade for such but we still need to know when to stop it. This is just a fragment of an example I'm very sure we all have our different experiences of where the past has steadily tried to bring negative energy into our lives but its out choice whether to let it, never forget that the present is a gift and the past is only but a memory and the future is stored with limitless possibilities.
Think about thia the next time you want to whine about the past instead convert that energy into something positive and take control of the now.