Nothing. I believe that there are two types of significance in life, Vertical, which stretches through time and history, and Horizontal, which spans all those around you, in your current lifetime. I notice that most people strive to achieve Vertical Significance by becoming famous or doing something that makes them "matter". Personally, I am going to focus on my Horizontal Significance, and just make sure I enhance the lives of those around me. If I do it right, that will be a legacy in itself.