I'm naturally (maybe unnaturally) introverted, by nature ("on the spectrum" introverted).
You'd never know it, though, when interacting with me. It's been totally sublimated.
But it is exhausting, keeping up the extrovert. When I would get back from business trips, I'd be totally burned out, and it would take me days, to reestablish a baseline.
I'm happiest, and most energized, when I'm by myself, at my desk, working on software.