Can confidence be acquired?
So what do you do?
If you want to see the stars, you need to block out other light sources. If you want to be a good public speaker, you need to silence the distractions. So to tackle them in turn...
1: The fear. Read back in this blog to find ways of removing the physical effects of nerves.
2: not really a presenter? Record your speech, play it back,listen to it critically and work on the areas you aren't happy with. Play it again, not bad eh? Remember that feeling.
3: Good speakers? Learn from them. You don't leave the house every day expecting a battle do you? You can copy ideas, listen to techniques and even avoid failures by studying other speakers. The experts can help, not hinder.
As for the stars, they are there if you look hard enough.