It's more than the expected pre-show jitters. It's not that "stage fright" nervous energy that can be channeled into putting on a great show. It's not just adrenaline.
It's that thing that also happens when you aren't on stage (or about to step on it). It's just extra, extra annoying when it decides to pop up at this time. It's that thing where you feel like a ghost that was just thrown into a body after not being inside one for a long time. How do I drive this thing? The ghost keeps asking itself. How do I make it talk? How do I move the feet? How do I search through old files? How do I read the old files and use them?
Everything feels like it isn't real. And somehow, everything feels like it doesn't matter completely while completely and utterly mattering all at once. And it's like you feel each individual eyeball on you. And it's almost as if each individual eyeball hurts. Not that you have literal, tiny painful spots on your body, but it somehow hurts in spirit.
And then there are the things that do hurt. Your muscles are tense and you didn't even realize until they start to get sore. You open your mouth to say a line and your jaw cracks, and you hope that nobody heard it but you. But then you remember the microphone on your cheek that makes you look like a strange theater-hipster-drive-thru person and you really hope that nobody heard your jaw crack. And then all you can think about is whether or not anybody heard your jaw crack and you're going through every possible excuse for how they couldn't have heard it while simultaneously going through every possible excuse for how they could have heard it. And then you wonder if they even know what that sound was, and you make a list for everything else they could have thought it was. And then you realize you weren't paying attention to anything that was going on.
And then you're backstage and you feel like some weight is crushing you. And the sooner it is that you'll be back onstage, the heavier the weight gets. And it's not like you don't enjoy theater, because when your mind doesn't go to this place you actually, dare you say, enjoy this activity. But it's in those moments where you feel like some third party has grabbed your mind and held it hostage, maybe tied it up and pointed a weapon at it, that all the chemicals in their go haywire. And you know that it's just a play that people will barely remember in 48 hours. But when your mind's being held hostage, you somehow know that, but don't know that at the same time.
Back on stage, the ghost version of you is awkwardly trying to drive this body. Despite trying to pay attention to the scene, you get hung up in how awkward you must appear physically, socially, and vocally (if vocally awkward is a thing, though if not, it is now). And you know that someone, someone is going to bring this up at some point. And someone, just someone won't let you hear the end of this. And you watch the other people who seem to have so much grace and you wonder what things would be like if you're mind didn't go into this mode. You wonder how good you could be if you didn't have this extra fight. But you do have this extra fight. And you're acting uphill with every scene.
And in the end, maybe a B-grade performance from you means more than an A-grade performance from someone who doesn't have this extra challenge. And just like a Winchester, you just have to fight off one demon at a time.