Emotion
I like this one because it teaches us to give our anxiety/stress an identify. It's recognising it's there, it's physical feeling and it's difficultly for it to go away, so what we do instead is learn to feel it, recognise it, pin point it, and take control of it. It enables us to be ore strategic, rather than letting it rule us. Even though it may not go away, we are at least able to give it an identify and remember that we are in control, not it.