It is understandable why we should be nervous when confronting an audience who expects us to do something, whether it be give a speech, sing an aria, or perform a dance. They have the expectation that we will entertain them, and we feel the responsibility to do it well. At least we should. I had a teacher who once said that anybody who was not nervous before a performance was either too stupid to grasp the implications of the situation or just didn't give a darn. Most self-respecting humans want to be judged well in their endeavors, and so a certain amount of angst before any kind of "performance" is absolutely normal.
As a child, I was rather quiet, and assumed, maybe because I was told so, that I was shy. Looking back now, with the decades of experience that have intervened, I realize that I was more cautious than timid. My style is to check things out before jumping in, and it took a few years to assess the world. One of the most complex skills any human must learn is public relations. Analyzing and adapting to our physical environment is a snap compared to gaining the diplomatic skills necessary when dealing with all the different people we will eventually meet. I was given plenty of instruction in the delicate art of conversation (children should be seen and not heard), often reprimanded when I made some snide comment within earshot of my elders, and was occasionally ridiculed for being loud and boisterous when I let my guard down while having a good time. Of course, my childhood was much like anyone else's, and it was my particular personality tendencies that caused me to remember those individual life lessons so well.
Stage fright is generally not an issue for young kids, as it is a learned reaction that takes time to discover. Most kids like doing what they enjoy and at first do not realize that they are sometimes being judged by others. Then they learn that they are, and there is that long awkward stage when they figure out how to deal with this knowledge.
My first well-remembered episode of performance anxiety came in 6th grade when, as a member of the school band, I had to play a clarinet solo at the annual Solo & Ensemble Contest. I had started band with several of my friends in the 5th grade and, for the first year, we simply played in a big group. I, for one, was more concerned with figuring out what all those black dots on the page and all those keys on my clarinet actually meant and did. No room in my limited mental landscape for such abstract concerns as how the horrid noises I was making were affecting the people around me. The solo had to be memorized, an especially challenging task for me, and I had to stand up to play it. This latter requirement shouldn't seem too important, but I was rather small and had very double-jointed fingers, especially my thumbs. Holding two pounds of wood and metal on one thumb for any length of time was so difficult that I usually supported the clarinet with my knees pressed against the sides of the bell while I was sitting. Trying not to drop the instrument AND play the right notes at the right time without the aid of a sheet of music in front of me was terrifying. I survived.
By the time I played my third solo, in 8th grade, I was much better at holding up the instrument and had learned a few tricks about recovering after I forgot part of my memorized piece. By high school, I was told by friends that I would get no sympathy from the judge because I didn't look nervous. For some reason, that small revelation was a turning point. If I didn't look nervous, why was I making myself feel that way? Surprisingly, I WAS able to reduce the nerve problem to the point that it seemed pretty minor. Common sense solutions included playing small mental games to take my mind off obsessing about mistakes, doing adequate preparation, and thinking about music as something that was for enjoyment rather than simply a contest to "win."
High school presented other chances for stage fright, including the terrifying Speech Class, which was a requirement for all students. Being given a topic in which I had no interest whatsoever and having to get up in front of everyone and convince them of one view or another was close to the top of the list of most horrible things I've ever done. I have no idea what any of my speeches were about, but I still distinctly remember that feeling of cotton in the mouth to the point of almost not being able to get the words out. Where does all the saliva go? I've never felt that at any other time. The funny (now, in distant hindsight) thing about that class was that, at about the same time, I was also delivering a major presentation in biology class. I was passionately interested in osteology and had no trouble filling an hour by sharing all the fascinating stuff I had learned about bones. I rehearsed my talk, taped myself to make sure I wasn't saying "uh" too often, and was so immersed in the topic that I completely forgot to be nervous. I later realized that giving that science lecture was more like playing music than giving a speech. And I enjoyed it.
Since my career as a musician involves performing, I obviously have gotten over the worst of the stage fright issues. One trick is to channel the anxiety into concentration applied to making any performance as good as possible. It takes a lot of energy to make music; it's sort of like an athletic event but without a winner or loser.
After high school, I did not do much public speaking. I gave clarinet master classes and lectures in my music courses, but they were less like making a speech and more like teaching private lessons with an audience. Thirty years of working in music education passed and I retired, finding the time then to devote to my other interests. Photography, taxonomy, and nature in general became my foremost activities. The slip into entomology seemed to happen without any effort at all. Then, one friend made a suggestion that I could combine my interests in photography and insects to give a talk to a local nature group, the Austin Butterfly Forum. I discovered public speaking again, this time without any stage fright.
There is a big difference in just giving a speech vs. speaking about something that is personally satisfying. There are probably times in anyone's life when they must do the former, and, as with any skill, some people are better at it than others. But it seems that sharing an interest or providing information on a pleasing topic, even if it involves getting up in front of a crowd and ... oh shudder ... SPEAKING, does not have to be a scary thing. To reinterpret the familiar cliché, talk about what you love and the confidence will follow.