Confidence does not require pretending the challenge is easy.

Pretending something is easy is not confidence; it is a bluff that has to be maintained. Real assurance can say plainly that a task is hard, that you might not manage it, and that you are going to try anyway. Acknowledging difficulty is what allows you to prepare for it properly.

Before your next demanding task, say out loud that it is difficult. Then plan accordingly rather than around your image. Honest assessment of the challenge tends to improve your odds against it.