B2N2 makes an interesting point when saying "nervous, excited and scared" because they all feel the same. The physical sensations are exactly the same, it's just what you choose to call it. Call it excited and you will be.
That said, everything worth doing feels a little bit scary when you first do it, even if that's just because you're afraid of whether you'll be good enough.
Remember, too, that anything worth doing is worth doing well and anything worth doing well is worth doing badly first.