His Mindset Changed!
So William took inspiration from what his master used to say after every failure, after every battle with losses in his team back then, "We will train, we will pour every sweat we have to get stronger, and in the end, we will survive and prevail! Raise your heads high up, we are the Fox guild!"
The moment he said his last piece, the one he improvised at the spot, he raised his fist high in the air, and shouted while releasing all the frustration swelling deep inside him.
And yet his shout was perceived in a different way to everyone else. They all shouted, raised their fists in the air, and shouted in defiance and courage.
They were excited about what he said, and the new members knew they made the right decision to be here. As for the old ones, they knew their master was the best master in the world.
His friends heaved a silent sigh of relief when they saw him do this. It meant at least he was having total control over himself, but they didn't fall for his words.