When I started doing court work, an old friend of the family who was a professional organist asked me if I ever got nervous before going into court. I said “yes, all the time”. He said it was the same for him before a performance, and if he ever stopped being nervous, it meant it was time to quit, because he no longer cared about it.
I agree with the comments about excitement that others have made, and sort of agree with Diogenes’s comment. I would just qualify it by saying that if you know what you’re doing, you also should know how things could go wrong. If you let that overwhelm you, you’re in trouble.
But instead, if you use that fear or anxiety to plan for contingencies (“What happens if the power goes out?” is a good one for a band to think about; “What happens if the judge doesn’t accept that part of my argument?” is one that lawyers should think about), then you are actually building your ability to go on stage, or before the court, and handle yourself professionally. you’ll be ready for the contingency you’ve planned for, and also in the mind-set to deal with the contingency you’ve not expected. You’ve turned that fear/nervousness/excitement to your advantage.
Me, I’m usually nervous before court, often in proportion to how much is at stake. Sometimes when I’ve been working late nights on the brief or factum, I’m muttering to myself that it’s time to look for another way to make a buck. The worst nerves are in the prep time - “who’s ever going to buy this dreck?” as I re-redraft my factum for the 15th time.
But it all goes away when the presiding judge looks at me and says, “Mr. Piper, we’ll hear from you now.” Then it’s showtime! If I’m in the groove, it’s just me and the judge or judges, having a debate. There’s no-one else in the court room. Tv cameras and bright lights? they just fade into the background.
And when it’s over, and I’m coming down from the high, I think, “Damn, that was fun! When’s my next case coming on?” and the cycle repeats.
And then I go to a bar, usually with co-counsel, and sometimes opposing counsel (if it’s been a civilized encounter, which it often is), and re-hash it all over a beer.