Many people I know of achieved success because they believed that they could do it. Self doubt and success never go hand in hand. If you are a businessman and have doubts about you achieving success, you will never be successful. People achieve success because they believe that they can do it. If they had an approach that they cannot achieve anything, they would not be able to achieve anything. The real key to success is to believe that you are going to succeed. Even if you do not succeed at the end, at least you believed in yourself this whole time. This is something that counts.