It is by presence of mind in untried emergencies that the native metal of a man is tested.

You find out what you are made of in situations you have never rehearsed. Practised competence is real, but it only covers the cases you prepared for; what shows up in the unrehearsed minute is something more basic, the capacity to stay collected while you work out what is happening. Nobody knows their own reading on that dial until it is taken.

You cannot practise the emergency, but you can practise the collectedness. The next time something small goes wrong, take one breath before responding and describe the situation plainly to yourself, so the habit is there when the stakes are higher.