The things that drive you. We're all driven by something to some extent. Need, hope, ambition. These are the things that we take into account as we create our perspective and formulate our personal belief system. And, at some point, some of us will get tired. Stop. While others will go on to succeed in their goals.
There are many differences between those who stop and those who keep on going. The primary one, however, is persistence. The need to simply keep on going, no natter what. And persistence, alongside perseverance, always deliver some result.