Why are you confident in certain difficult situations while being doubtful in others?
One reason is that you know what to do.
But, even if you know how to do something you often feel doubtful, afraid or insecure. Clearly, knowing what to do is not enough.
What you need is experience.
You need to know that you have successfully navigated difficult situations in the past.
This is why theory can’t replace execution. It’s why doing is generally more powerful than thinking.
Gain enough experience and you won’t have to act like you are confident – you will be confident.