Pace & Pause
Speaking professionally is usually about communicating information and knowledge – feeding the listeners what’s in your head.
Just as with feeding a baby, you need to ensure that you don’t feed too fast – or too slow – and that you wait occasionally for the information to go down.
Breathe slower and deeper.
If you are tense, especially somewhere in the lower limbs, this can lead to lower abdominal tension which prevents the diaphragm from dropping. This forces you to use the much smaller top part of the lungs – so small that you have to race to the end of the sentence so that you can take another breath. Establish slow, deep breathing before you start.
Use clearly articulated word endings. Just the effort of getting your lips and tongue around the all-important final consonant will put the brakes on.
If the audience needs a shake up, alter the pace. If you are losing them, alter the pace. Try going a bit faster on bits you are excited about and slow down to explain detail.
At the start, deliberately slow the pace. Or even pause (breathed) before you speak. The audience are processing all sorts of information about your clothes, shoes, hair etc. They also need to settle into the task of listening. Breathe in the audience before commencing.
Alter your delivery according to what you see. Pause when you see they need to take in a big thought.
Fill the pause with breath.
If you temporarily stop breathing then you will have broken the link between you and your audience.