Before you even start speaking you need to breathe.
The anxiousness many people feel before they begin to speak is directly related to the "flight or fight" emotional reaction that is taking place in their body.
The sympathetic nervous system kicks in and the adreneline starts pumping because the mind has told the body you are in danger. Notwithstanding that you may physically want to flee or have the floor open up and save you having to speak, you have to send a message to your body to stop producing so much adrenalin.
You can do this quickly by taking a deep breath - inhale for 3 - hold for 1 and exhale for 3. Do this until you feel calmer.
You can use the same technique during your presentation if you feel the nervousness returning or you start talking too fast.
Happy breathing and lots of it.
