Self-confidence is never a 100%, 24-7 field of bunnies and rainbows. Being completely sure of yourself all the time is not confidence, it's arrogance.
Self-doubt can be a brutal critic. We tend to give it a megaphone, and unlimited use of the mental chatter platform. We let it run rampant, crippling our dreams and debilitating our self-worth. However, kept in check, it is a vital tool to be used to keep us from becoming completely absorbed in how great we are. The truth is, self-doubt does not negate whatever amazing qualities we possess, any more than doubt that the Sun will rise tomorrow prevents it from doing so. These wonderful qualities still exist, whether you doubt them, or not. It's only your perception of them, and your likeliness to tap them, that is actually affected.
Building self-confidence is less about being sure of yourself all the time than understanding that self-doubt skews your perception of yourself, and learning how to shift that perception back into alignment with the truth – that you are a beautiful, flawed, ever-changing expression of humanity with an amazing gift to offer the world.
The key to finding self-confidence lies in the journey to discover that gift.