Lying to ourselves is more deeply ingrained than lying to others - Dotstoyevsky
In Arthur Miller's Death of a Salesman, Willy Loman is a man who won't face reality, constantly reminiscing, always looking back. His obsession with life as it used to be has caused him lose his grasp on the life in the present and has robbed him of his dreams for the future.
His opportunity to make a difference with his life was wasted. Living your life in the past is not only sad, it's dangerous. Why? Because you can have no effect on the past. It is what it is. Dwelling on it will only leave you frustrated