There's a trick, still learning it - you learn a piece so thoroughly it's like second nature, and then you do it in the moment and it's like you've never done it before.
This moment. Nothing else exists.
Sometimes you pull it off and sometimes not. Plus there's always the potential of blowing it - jumping lines, missed cues, the dreaded technical glitches.
It gives it all a sharp edge. The potential of disaster - embarrassment, humiliation, failure.
That's why it's worth doing. Because you are flirting with disaster, and then, maybe, if everything breaks your way, you pull it off.
At least that's the idea. And sometimes it's all so thrilling and rewarding just to stare down the threat of failure, and dance away on a cloud.
It's like finding the best drug ever invented.