Confidence is exactly like a muscle that can be built or depleted depending on the actions that you take. Realizing that building confidence in yourself is not only attainable, but entirely up to you is empowering and factual.
I have personally built my confidence, and I have watched as it began to erode and I rebuilt it again. While we cannot control what happens to us in our life, we absolutely can control how we respond to these external factors. Confidence is the one thing that changes everything.