Low self-esteem is the result of thought. The thoughts that lead to low self-esteem form part of what psychology calls your “Stored Knowledge” - the stuff you learned about yourself when you were young and impressionable.
Believe it or not, as an adult, you’re designed to pay attention to these thoughts - because, at the very least, they help you make it through the day. Remember, the brain is only designed for survival.
You don’t need to build your self-esteem or your self-confidence. You need to stop paying attention to the stored knowledge thoughts that keep getting in your own way.
You get out of your own way by learning how to pay attention to the here and now - the essence of proper focus. Once you start doing this you will begin to realise that all that was holding you back was your own thoughts. And that realisation alone will change your life.