Confidence. Fool hardiness. Mostly? A sense of play. Something that emerges and continues to emerge all the way through his good natured, even laughing, defeat.
It's accompanied by the whistle blowing.
"I am out of practice," he says, as he heads for the kettle and to make tea for the pair of them.
... Confidence and fool-hardiness. And doesn't that just sum him up? He should know better. He does know better. It's just. He's also realizing how very not worth it to him the caution can be.