Lack of persistence is one of the major cause of failure. Moreover, experience of thousands of people has proved that lack of persistence is a weakness common to majority of men. You may have failed thousands of times but at that time persistence will come to your aide. Without persistence, you will be defeated, even before you start. With persistence you will win.
You will have to be persistence in constructing the model of your success. Be persistent no matter how slowly you will move at first but you have to move. Cultivating the habit of persistence is like having insurance against failure. No matter how many times you have defeated, you will finally arrive up toward the top of ladder.