One of the most useful skills I have ever seen is the ability to trust yourself in any situation, especially in a challenging one. It helps to become more confident and calm, regardless what's happening around.
Trusting yourself isn't something you can do, it's the state that fully contains this moment, therefore It can only be experienced. To become closer to it, you can ask yourself right now, "Do I trust myself?", then become very alert for a while to get the answer. It might take 30 seconds or so, but it's, definitely, worth trying because this simple question might change your life.
Note, whenever you can't concentrate on what you're doing, you've stopped trusting yourself.