We speak, we sing - it's all the same thing

We speak, we sing - it's really the same thing.
  We use our voice -it's an instrument.   We can make lots of lovely sounds - no real need for words. Just sounds. The centre of your being - your diaphragm breathing - is what generates your most attractive voice.  If you breathe from your upper chest - you'll have nowhere near the capacity of breath as from your diaphragm.  And  if you are very anxious, your shoulders might end up touching your ears!
When you are asleep you breathe naturally from your diaphragm.  Ever watch a cat sleeping? their breathing comes from the diaphragm.  Diaphragm breathing is the very first step to managing nervousness when you are speaking or singing in public.  Did you ever see a cat that was stressed?   You, too, can de-stress by using diaphragm breathing.
Did you see the movie "The King's Speech"?  Did you see the Queen sitting on the chest of the King?  To help him strengthen his diaphragm.
So, here's a tip - when you are driving in your car - you probably sing along a bit to your favourite music.  Try breathing in and pushing your diaphragm out at the same time.  Do that a few times for a very energising, but calm, state of mind.  Go further and say "Kah, Hah, Gah" nice and loud -it's great exercise for your voice!  Your unique voice. For more info on breathing from the diaphragm and why it's good for speaking and singing check out:  http://www.ask.com/questions-about/Diaphragmatic-Breathing