Writing on the thnk.org site, Robert Wolfe makes an interesting observation about how storytelling can gain power when the teller reflects the hero's journey in the way he or she tells the story:
This journey is a structure underlying many of the world’s tales and myths, uncovered by Joseph Campbell. In short, the hero leaves the safety of the village on a quest and deals with failure and near death to eventually overcome his or herself, find the elixir, and come back a changed person. Stories are about going out on a limb and they are about change. So during the course of telling of a story, we ideally expect the storyteller to make that journey in front of our eyes. Hence we don’t want them or their bodies to be in a position of power throughout the telling. In a sense, it should be a journey away from safety, to where it is unknown and dangerous and then back to find the world is changed, either outside or within. From strength to vulnerability and back again, or to somewhere else altogether.
When I thought back to some of the best pitches and presentations I've heard, that rang true.
If the person doing the pitching hits you with 100% of their power right from the start, it can feel overwhelming, like they're over-acting or trying too hard. I experienced this once at a conference. At a time when most of the audience was still kind of waking up (many came in with cups of coffee), the first speaker of the day launched into her talk with maximum energy and enthusiasm and expected the audience to be with her right from the start. We weren't. Her attempts to get us to respond to her questions (which we all recognized as rhetorical anyway), fell flat. People near the doors fled.
In a presentation, the introduction of the speaker can be considered the 'normal' phase, the speaker coming on to the stage is the call to adventure. The speaker's initial nervousness reflects the impulse to resist the call, and spotting a friendly face in the audience is the equivalent of finding a mentor.
In a pitch, the small talk preceding the actual pitch is the normal, then the start of the pitch is the call to adventure, a time when it's natural to feel a bit nervous, and noticing that the other person is listening and perhaps nodding helps you feel you have an ally. At points in the story where there is maximum danger or conflict, your body language can reflect that as well.
In either situation, we can warm up to the story, tell it in the way that's natural to us and mirrors the content, gather strength from the attention of the audience, and finish strong.