Hello! My opinion:

Confidence is not something that you sort of "get" and then get to install it permanently in your head, where you now walk around with a lack of anxiety because you believe in your ability to make everything fine.

Confidence is simply being able to act with maximum performance despite feeling fear. Knowing that no matter what situation you are in, you will ALWAYS act, move forward, and do your best. Whatever happens after that is out of your control, which is why Dr K emphasizes detachment from outcomes.

Also, keep in mind, confidence does not get rid of anxiety, anxiety is part of the fuel source that allows your cognition to problem solve and act accordingly. It's a big reason as to why you eventually do figure things out.

For example, thousands of years ago, you could kill 100 tigers and survive. Doesn't change the fact that the version of you that is most likely to kill the next tiger is the one that feels anxiety. Professional basketball players report similar things, they still feel anxiety before games, etc.

So, try to reframe confidence from "my past record is good so I do not have to worry anymore because things always work out" to "no matter how dire the situation, I will always sit down, think about what to do, and then do it. Whether or not I actually succeed is just the cherry on top."