"Change your thoughts and you will change your world", Norman Vincent Peale.
One thing you must understand is that positive thinking only forms the first half of the power of your mind.
The other half of the power lies in the actions you take once you have positive thoughts. This is where your willpower comes into play. It is your willpower that determines whether things get done or not. It is this willpower that corresponds to the inner voice that tells us to take action to make our thoughts come true.
Realize that your mind and your willpower are not distinct from each other. If you do not see it in your mind, you will never be able to manifest it in reality. You must have a completely positive mindset and the conviction that you belong and that you will achieve any dream you desire.