There is SO much truth in this!
I was encouraging someone over the phone yesterday and I related the story of how many years ago a speaker making the point that you cannot let lack of confidence stop you from trying something new.
He asked us to recall when we were first learning to ride a bike and we told the person teaching us not to let go of the seat until we were ready.
He said you cannot have confidence until you aquire some competence and that only comes from doing.
So the sequence is as follows:
First you have to do. No competence. No confidence. Just the courage to do.
With repeated doing, failing, learning, changing your doing to improve it, you gain competence.
And as a result of gaining comptence to are now confident.
Look over any skill you have and I think you will see the truth in this.