I am old enough to look back to see the many things, not all pleasant, that have happened in my life. If I had been shown them at the beginning before they happened, I am not sure that I would have wanted to live my life. Once I know God, the past does not matter anymore because all that has happened has lead me to the happiest time of my life. In the same way, joy in heaven would make us forget our life on earth. With God, it's getting better and better.