Relax and look like a genius.
You can make yourself the calmest and smartest person in the room.
Whenever you see an athlete about to perform, you will notice that they take a deep breath before they begin. For example, a well-trained basketball player getting ready to shoot a foul shot will always pause to take a breath before stepping up to the line. One of the reasons for this is to help calm his nerves so he can focus on the shot. Presenting produces at least as much anxiety as foul shooting, so take a nice deep breath just before you start.
We only use about two thirds of our lung capacity in normal breathing. Fill those lungs with air and you fill your brain with oxygen. Relax! Remember, no one will know you are nervous or whether or not you have made a mistake unless you tell him. Give your brain a chance to help you by sending it all the oxygen it needs. Breathing helps you to focus and relax. A deep breath can wake us up, calm us down, and make us feel good. And it is free and easy to do. Try it. You have nothing to lose but your excess nervousness.