You can have a pretty good presentation going and damage it severely with distracting habits. I've been around for a while, yet I still watch myself on videotape whenever I can to identify anything I may be doing unconsciously that may hurt my presentation.
Some problem areas you want to watch for are
Pacing back and forth
Jingling coins in your pocket
Jingling bracelets or jewelry
Playing with your hair (normally done by women)
Playing with objects (pointers, markers, etc.)
Holding on to the lectern or table for dear life
Rocking front-to-back or side-to-side
Standing rigidly in one place (this would surely create ZZZZZs)
Speaking with your head down or bowed
Locking hands together or twiddling thumbs
Tapping your fingers
Pushing up your glasses
Almost all of these problems can be improved significantly and immediately. The simple realization that you are doing them will start the improvement process. To eliminate them completely may take a little extra effort or the help of a competent presentation coach.
Trick: Get in front of a mirror. Hold light dumbbells or heavy books in your hands. Start delivering your talk. When the books or dumbbells move, you have located real gestures. When you first try this in an effort to eliminate bad habits, you will notice that your mouth won't go. Don't worry. Eventually the bad habit will give up and your mouth will do just fine. Note: Use a heavy enough dumbbell so you don't smash yourself in the head when you try to adjust your