Do you approach things from a place of deficiency or abundance? Is your attitude, I need more practice, need more preparation, need more experience, need more knowledge, need more training, need more learning? Or is your attitude, I know everything there is to know, I don’t need any more practice or preparation, I am entitled to the outcome, I consider myself to be at my best?
Both are a detriment on their own or in extremes, but mostly a detriment if it’s not an honest self-evaluation. If you doggedly prepared but have an attitude I still haven’t done enough, you’ll lack self-confidence. If you haven’t really prepared or have soft discipline, but you feel you’ve done everything you can and you’re already at the pinnacle, then you’re insulating yourself in arrogance and over-confidence.
Maybe something in the middle is a more honest evaluation, don’t be so hard on yourself but don’t be too generous with yourself.