I am shy. I'm more outspoken than I was 10 years ago, but, on the introvert-extrovert spectrum, I'm still an innie. Those moments when I feel the need (or see the opportunity) to express myself are rare. However, when they come, I experience some strange physiological changes: my skin starts tingling, and my extremities start to sweat and cool. If it takes me a few minutes to write my thoughts down, or speak them, or even complete some sort of public test (of skill or strength) - the key is expressing myself to others - I'll become so cold that I'll start to shake. This can be really annoying, if, for example, the test is a multiplayer game of Halo: sweating all over my keyboard while shaking my mouse makes it tough to shoot the enemy.
Am I alone? Again, it's an excitement, as opposed to an anxiety. Believe me, I know the difference. In Grade 9, I had to speak on my favourite song for a few minutes in front my (English? Social Studies?) class; by the end, I was getting one or two words out between gasps, seconds from hyperventilating. That was anxiety, and my public speaking is much improved today, I'm happy to say. But this excitement is still distracting. Sometimes I shake so badly that I can't type. And my wife loves it when I hug her with my corpse-like hands. :-)