It goes right down to your core, because you know that in going up and presenting your work will seem markedly inferior, and yet you have to make a show of it. It strikes at the insecurity that is buried within us, where we constantly feel that we are not good enough next to our more accomplished peers. Nobody wants to go up and look bad, and yet what do you know, you're about to become that person.
In short, it is a shit situation.
But I feel that such a situation really calls for courage and conviction. There is no getting around the fact that no matter what you do your work will be a shade of what has gone before. However, it takes a lot of courage to know that despite this, you are proud of what you have done, and hence you go up and put on the best show you can despite the fear eating you up inside. It also takes a lot of self-belief to have faith in your work and believe in presenting it the best way you can despite knowing it is subpar.
In front of a crowd, it is never any less intimidating, and I never feel any less nervous. But when the presentation begins, I find that I forget everything that has gone before, and the stage becomes mine. I make it mine, because what's past is already past, all the attention is now yours, and it is up to you to decide what you want to do with it. I read somewhere that courage is not about being without fear, it is about having fear and yet dealing with it, and I think it is very true.
Anyway, I think a personal philosophy of mine comes in best when faced with something like this. It's called "Salvage what you can." You may not get 10 out of 10, but that is not an excuse to not try and get 7 out of it, because 7 is still better than 0. Slow and steady wins the race anyway, and no war is won on single battles.