This is the question you have to ask yourself time and time again. If you learn to do that the right way, the question is not about you having success or not, it's more like how soon you will have it.
My turning point was reached when I realized that my daily steps and actions where controlled by my daily habits. It is as simple as analyzing your habits, all of them (not easy though) and make sure most of them brings you closer to your goals and also that non of them brings you away from your goals. There is a Swedish saying: "You are what you eat". It may be true but I'm absolutely convinced about that you are what your habits make you.