A true NO ZZZZZs presenter doesn't feel that he or she must jabber away constantly to keep the audience awake. Skilled presenters use silence to add to the effectiveness and polish of a program. Theatrical folks have identified a whole bunch of neat pauses which I'm sure they have a ball playing with. I'm only going to address some of the most obvious and important ones here.

Short
The shortest pauses, which last anywhere from one-half to two seconds, are for the simple purpose of separating your thoughts. All you have to remember is to slow down. Give the audience a fighting chance to absorb what you are saying. Change your voice inflection slightly at the end of each thought to cue the audience the next thought is coming. Also, use a short pause before and after any phrase or word you want to emphasize. (Refer to this website's
'How to Deliver a Punch Line' article,
for reference.)

Spontaneity
Another neat pause is known as a spontaneity pause. This is a planned 'unplanned' pause used so that you don't look too rehearsed. You might apply this pause when you want to pretend to search for a word or phrase that you already know.

Long
Long pauses of more than three seconds are very powerful. They command the audience to think about what you just said, that is if what you just said was worth thinking about.

Please[pause][pause][pause] don't be afraid to be quiet once in a while. It can dramatically increase your impact.