Put in the work. When you’ve put in the work and you know you did everything you could to prepare for an event, interview, or presentation, your confidence will be sky-high.
The reason is that you know you’ve genuinely done everything you can and there is a real, deep, and abiding comfort in knowing that and in believing that in the way that you believe the sky is blue. You absolutely know you did everything you could.
I stress that point because it’s very easy to hit a deadline and convince yourself that you've done everything you can while you know deep down in your heart that you could have done better.
The solution is to do better from the beginning.