After careful consideration, I have understood the source of confidence. I used to believe that it came from external sources, from how one is spoken to (praise or lack thereof), how one is treated, and the manner in which one is raised. That is partially true when one is not fully conscious, or yet to achieve a higher state of consciousness that comes with age, potent experience, and/or focused meditation.
People often seek confidence from their environment, in the form of recognition, acknowledgement of some quality or effort, or even basic attention from the opposite sex. I believe this to be a futile attempt at attaining something which really comes from within. If you depend on the external for confidence, then it can take it away from you just as fast as it can give it. In that scenario, one becomes dependent on external sources for self-esteem and feelings of self-worth.
It is my belief that true, unshakable confidence comes from understanding, accepting, and living in alignment with who one wants to be, approaching the ideal self- self-actualization.
What one did in the past undoubtedly can have an influence on this alignment or misalignment, but that is part of the process of accepting oneself, as what one did regretfully in the past would not be repeated in the present, as the conditions, situation, and awareness that exist now would not allow such actions to take place.
Look within to rediscover your potential for true condifence. Confidence in who you are, and who you are aiming to become.