"Learning often consists of scrabbling around in the undergrowth, on the edge of your comfort zone."
I came across this educational blog post recently and I think it emphasises a really important point: learning is often uncomfortable, and challenging.
Before we can learn how to do anything new, we have to be prepared to admit that we don't know it and/or can't do it (yet). This takes confidence and self-belief, as well as faith in your teacher that they can get you there.
Those who are hamstrung by fear, or expectations of failure, can't let themselves go. You have to be prepared to jump in there and just try, without any guarantee of success.