Or maybe she has to constantly work at it. Self-confidence. We don't lean on the idea of being self-confident; we act on it, routinely. Our mind is like a bank. Building self-confidence muscles involve depositing things into our mental bank that form an empowering belief system.
We continue to accept others' admiration and expressions of "you're so confident," but we do the work--we always do the work--to make sure that our habits and behavior reflect our inner confidence.
What is this work? Maybe it's a good workout or reading a self-empowerment book. Perhaps it's ten push-ups a day, a ten minute meditation, or visiting with a friend.
The work is doing what makes us feel good and depositing that good feeling into our mind. We pretty much laugh our way to the bank.