Do not try to speak too long without renewing your breath. Nature cares for this pretty well unconsciously in conversation, and she will do the same for you in platform speaking if you do not interfere with her premonitions.
A certain very successful speaker developed voice carrying power by running across country, practising his speeches as he went. The vigorous exercise forced him to take deep breaths, and developed lung power. A hard-fought basketball or tennis game is an efficient way of practising deep breathing. When these methods are not convenient, we recommend the following:
Place your hands at your sides, on the waist line.
By trying to encompass your waist with your fingers and thumbs, force all the air out of the lungs.
Take a deep breath. Remember, all the activity is to be centered in the middle of the body; do not raise the shoulders. As the breath is taken your hands will be forced out.
Repeat the exercise, placing your hands on the small of the back and forcing them out as you inhale.
Many methods for deep breathing have been given by various authorities. Get the air into your lungs—that is the important thing.
The body acts as a sounding board for the voice just as the body of the violin acts as a sounding board for its tones. You can increase its vibrations by practise.
Place your finger on your lip and hum the musical scale, thinking and placing the voice forward on the lips. Do you feel the lips vibrate? After a little practise they will vibrate, giving a tickling sensation.