Yes, I understand this principle. I think it works for many people. You're one of them. But I'm not saying he should hide. I know that hiding leads to more anxiety, self-loathing, avoidance, and likely worse stuttering. Only saying that if the slightly less cold water is still plenty cold, but at least not paralyzingly terrifying, can't that be enough for now? We are not all the same; there can be somewhat different routes to the same place.