Yes, at home.  If you get caught trying this in the work loo, your colleagues will recommend a psychiatrist.

This is for you if you suffer from symptoms of nervousness that are obvious to your audience. Examples: a nervous smile, a tremor in your voice, speaking too fast and without pauses, a twitch, or very little body language, a reluctance to look directly into people's eyes.  If any of your symptoms are like those, then this cure might work for you.

  1. Pick a serious topic you could speak about for about 20 seconds.
  2. Imagine what you would look and sound like if you were even more nervous than usual. Now look in the mirror and speak, deliberately exaggerating your nervous symptoms. (Just exaggerate slightly, don't turn yourself into a clown.)  What you're doing is externalising and objectively noticing your own symptoms.
  3. Reverse it. Strongly imagine what you would look and sound like if you were confident and really wanted the audience to get your message. What would you be doing with your eye and head language? Your hands and arms? The rest of your body? How firm would your voice be?   Now look in the mirror and do that.
  4. Alternate 2 and 3, until you're comfortable with 3. Now think to yourself, Could I make that (3) happen in front of a real audience?

The method works for two reasons.  First, you're showing your own brain the difference in symptoms between nervousness and confidence.  Second, by practising the symptoms of confidence, you're building into your brain the circuitry of confidence. 

Keep building and the act turns into reality. Make confidence a habit.