How do you deal with being nervous in the moment?

So, a common theme around here is that we need to be independent of the outcome, and cool and collected. That being nervous and/or anxious will make the person you're with feel that way too.

Now this is all well and good, but suppose that you tell yourself with your conscious mind that you don't care, that the outcome is unimportant, but subconsciously and emotively, you do care and are incredibly nervous. In my experience, one does not simply stop being nervous.

If you're out with someone, and you're already rattled, how do you deal with that? I think that's the question I'd really like answered. I know we're supposed to have this calm, abundant mindset, but you can't just automagically change up your conscious paradigm structure and expect your subconscious to just go along with it without reaistance. That takes time.

Getting nervous is a foregone conclusion. It will happen. How do you deal with those nerves in the moment when you're out with somebody?