There is no doubt that in order to accomplish a goal you must firmly believe that you CAN and you WILL accomplish it.
So, the next step is “How to put my brain in the right mood, to firmly believe it.”
You can try to repeat to yourself all day “Yes I can, Yes I can, Yes, I will”, but research has shown that the best way to do it is by building yourself an accomplishment history. The best predictor of your future behavior is your past behavior.
Banks and other financial institutions are well aware of that. They are seriously in the business of making money, and they can’t afford to take risks. They make the decision of weather to lend you money or not based on your credit history. The way you behaved towards paying your bills in the past is used to predict how you’ll be paying your bills in the future. Is this always true? Not necessarily, but for most of the cases, it is, and that’s what matter. They cannot afford to play with individual cases.
The same way you need to make your bank believe you’ll be paying them back, you need to make your brain believe you are capable of doing it, and that chances are high that you will eventually do it.
The best approach to do it is by building yourself an accomplishment history. Start small and let it grow over time. Set yourself small goals and learn how to appreciate what you have done by the end of the day. Keep it consistent. The results will be amazing.