Self-confidence is a result of day to day decisions of whether you will follow through for yourself - or not. When you follow through you begin to trust yourself and your abilities. When you don’t follow through you lose confidence in yourself.
Self-confidence comes from your thoughts about yourself. When you don’t do what you tell yourself you will do you probably have thoughts like:
I just can’t do that
I can’t succeed
I’m a loser
Wow, I suck
Those thoughts are not going to lead toward self-confidence.
On the other hand, there are thoughts we can choose to think that will lead to self-confidence. Consider trying on some of these thoughts:
I was made for this
What others think about me has nothing to do with me
Worry only pretends to be necessary
I am capable
I have my own back
Those thoughts have the capacity to produce a feeling of self-confidence.
When we think thoughts that create a feeling of self-confidence we behave differently. Acting from a place of self-confidence produces results that are different than those we produce when we act from a place of fear or lack of confidence.