I'm also curious where you get your information.
I'm currently studying for my Master's degree, and Friday I have an exam about more than 80 research and review articles, all related to sports and achievement psychology. (And obviously I've done a bit of reading before this course.) And your statements make me raise my eyebrows.
One thing you say is that a person's physiological response will always stay the same; only the interpretation of the arousal changes. Do you have a source for this? In my own life, 10 years ago the thought of kissing a girl twisted my stomach and froze my whole body in fear. Now, I kiss a girl in a bar without any difficulty. I do not feel anything close to the arousal I felt back then. You're basically saying the same with "Whereas my anxiety used to overwhelm me, now it's subtle. It used to scream in my ear, now it's like background noise." Sure, there's still a little bit of anxiety sometimes, but both the physiological response, as well as the interpretation of that response, changed, in my opinion.
What you say reminds me of this: http://en.wikipedia.org/wiki/Reversal_theory
But that's just one theory about arousal/anxiety among many, with mixed evidence and no real absolute truths, just like every other fucking theory. (Frustration
) Although I do like the idea of reversal theory, and it makes sense.