True confidence isn’t found by believing in yourself. That’s just ignorance, aggression, bluster, and self-deceit. You don’t steady yourself by grasping yourself tighter and tighter.
Real confidence comes from fixing your eye on something bigger than yourself, outside of yourself, and grabbing hold of that. If you’ve grabbed something big enough and solid enough, it will steady you and give you all the real courage and confidence you need.
You won’t find confidence by pretending at qualities you don’t possess. But you might develop it by pursuing something that demands it from you.