Funny how these work together. In assessing when I perform at my best vs. my worst there are a few clear lines I've noticed.
I perform at my worst when feeling hyper *self-consciousness (**Self-conscious introspection is a hindrance) -> *Feelings of self-consciousness manifest from *insecurity -> *Insecurity is heightened by feelings of *being judged. Note - I said feelings. *Essentially all this happens in my head and I'm my own worst enemy at times. In my experience getting aggressive with a state change is the best response since I'm hyper-competitive by nature though I would imagine healthier responses exist.
I perform at my best when:
- I don't care what others think
- There is no feeling of being judged
- Confidence and smiles overcome all
- I face the challenge with excitement and enthusiasm - I'm ready to bring it
This really distills to confidence versus insecurity. One metaphysical challenge some folks deal with is the fundamental 'badness' of confidence vs. the 'goodness' of humility. But that's a false binary. Confidence and humility need not conflict. Humility indeed is a two-way road and should extend from equal footing. Confidence allows one be to more genuinely humble since they have the option of not being that way (they could be an arrogant SOB) whereas a lack of confidence cuts off that option.
Another re-framing if this is a challenge for you at work:

Confidence is an armor to protect the good on the inside. It's a baseball mitt - if you want to play ball you need to absorb those fast balls. Remember that this is all for joy and doing good. Playing ball at the highest level is a joy.