Your brain, particularly your subconscious mind, has one job: to help you succeed at whatever you're focused on.
The problem is it can't distinguish between what you want and what you're thinking about. Feed it constant worry about failure, and it will diligently organise all your cognitive resources to make that failure happen. Tell it you're not good enough, and it will find creative ways to prove you right.
This isn't mystical nonsense — it's how attention works. Your brain notices what supports your dominant thoughts and filters out what doesn't. Expect rejection, and you'll spot every eye-roll while missing genuine interest. Assume you'll mess up the presentation, and you'll focus on every stumble instead of the moments you connected.
The unconscious mind is remarkably loyal. It wants to deliver exactly what you've convinced it you're after.
The question isn't whether your brain is working for you or against you — it's always working for you. The question is: what have you taught it to optimise for?
What story are you telling your most devoted ally?