True source of Confidence
Most importantly, confidence comes from the Lord your God who created you, gave you the skills, knowledge and strengths. As a consumer, are you not choosing the product based on the brand or who the maker is? When you buy from a tested brand, you are confident that it's good quality. What more about our Creator, we are wonderfully made. If you believe that the same God who gave you the confidence before, will do the same today, what else could go wrong? I remember my old motto, "I will do my best and God will do the rest". We hold on to His promise in Proverbs 3:6 - In everything you do, put God first and He will crown your efforts with success.
How can I create confidence?
Second, it is important to Act Confidently. Our mind reacts to what our body does. If your head is down, your muscles are tense or your shoulders are hunched, your mind will sense your self-doubt. So always make sure that your body language and your communication with yourself and others portrays confidence. Even when you don't feel confident, act confidently.
Finally, realize you don't need other people to tell you that you are good. Back to the athletes example, many of them wait for their coaches to tell them that they are good in order to believe in themselves. You may want others to tell you that you are good, but it's not something you need. Believe in yourself and believe in the One who created you and destined you to be great. Set your mind that you have that confidence within. Whatever your mind conceives, the body achieves.
Choose to be confident. You have a reason to be.