For most people, the way we learn is tied to our experiences. I won't go into the neurobiology -- and you don't need neurobiology to know this -- but things are particularly memorable when they have an emotional signature attached to them.

Overachievers have a particular and exaggerated fear of failure. They do what they can to prevent it. They remember the instances where they did and aim to prevent those in particular. This can be exaggerated, a very common error in human perception (availability heuristics). If something rare but terrible happens to us, it no longer becomes inconsequential and we are predisposed to look for it much more than its actual probability.

In any case, failure is a potent learning tool. It is a very human learning tool. Mistakes are arguably the main way we learn. You are bitten once, remember the pain, and remember never to avoid what bit you if you don't want to be bitten. You shouldn't impose a hideous amount of fault on yourself every time a mistake is made: place the emphasis on learning from it.

I'm constantly being reminded how I can be handicapped by the lack of confidence an instance of failure can inspire.

I failed, recently. I was asked to ask some questions from a patient, then examine his peripheral pulses. I went to his bed and called his name: the problem was that it was the wrong patient who had a very similar sounding name to the patient I needed, who was in the bed next to him. So I put this man through an examination that included feeling around his groin unnecessarily. (I'm very thankful for the practice as I'm not in the habit of doing that sort of thing and this clinical skill is important, however, so not all is in vain.) I luckily discovered my mistake later, when recapping with the doctor who asked me to do it.

So I've learned from this. I'll have to be more thorough in using little details to check and double check identity. 'We've all done it,' the doctor reassured me, sharing some near misses early in learning prevented by double checking later in little ways, especially with another member of the team.

Trial and error is hugely important in human learning. 'You're allowed to make mistakes and you should make your mistakes now while they don't matter, while you're students, so you don't make them later' we have not been told once, but repeatedly. It's hugely important not to make any later, when it truly counts.

I have to remind myself of that. That I'm human, just like all the others who make mistakes too. That I can do this. That I'm learning. That my mistakes are even more important than what I get right when it comes to practically applying things in life, as opposed to learning things in simple theory. That what I have to do after my failure is process it, learn from it, then get back to the stethoscope and be confident, because I'll be better than ever now and what I have to focus on is make sure I've done what I can to stop it from happening again.

Do what you can to prevent them. However: Make your mistakes and learn. Make more mistakes and keep trying to learn. You'll get there with their help and you'll get there much faster the more you're afraid of making them.