So what is the big lie that you have been told your whole life about public speaking? It may even be a lie that you have told yourself! The lie is that somehow you have to be born a speaker. That is complete baloney!
I can say that I have worked with thousands of speakers all over the world and some of them are the best speakers in the world but when they come in to start working with me they all think that they are awful. They all get nervous in front of an audience. Even if you look at some of the greatest speakers in history and read their biographies, you will learn that they were in fact horrible speakers. John F Kennedy was considered a horrible speaker when he was a member of the Congress. He was known for his head down reading. Even as a president, you could see that his knees would be knocking together and his hands would be shaking. Barack Obama was not a very good speaker just a few years before he ran for the Senate. He was considered to be a boring law professor lecturing in a very boring way.
So anyone can learn to be an excellent public speaker and I have seen quick transformations myself. I have helped people with that so I urge and beg you to not tell yourself that you are not a natural speaker- that is simply a way to let yourself off the hook. If you are not 7 feet tall and you tell yourself that you are not going to be an NBA centre, then fine, you are on good ground. But if you had to give a presentation, do not tell yourself that you cannot be good because you are not a natural speaker. The first step to becoming a good speaker is learning and practicing on a regular basis.