That is why lecturing or presenting in front of a professional audience is one of the most common tasks of a researcher, in addition to publishing of course.
Not everyone is born to be a charismatic speaker. Most of us have heard lectures characterised by monotonous intonation, insecure non-verbal behaviour or poorly designed slides that distract from the actual subject matter. The audience might not always be willing to pay attention to the scientific content of the lecture when voice, body-language and presentation skills do not meet professional standards.
Presenter’s authenticity, a logical structure, and the focus on only a few key messages are key to a convincing presentation. The more you can inspire your audience the less you torture them and the more competent you appear.