Stage fright is not a character flaw; it is a body misreading the room as a predator. The adrenaline is real, and the goal is not to eliminate it — speakers who feel nothing are usually worse — but to give it a job. Every technique that actually works converts fear energy into preparation energy.
Adrenaline has a schedule
Nerves peak in the minutes before you begin and fall steadily once you are moving. So do your hardest work before the room: arrive early enough that the space is familiar, take three slow breaths with long exhales, and know your first three sentences so cold that no amount of shaking can dislodge them. Confidence is often just the first thirty seconds going well.
Built for the quiet ones
The example speech "A Case for the Quiet Ones" was written for exactly this audience — people whose best thinking happens in preparation, not performance. Read it, then steal its permission slip: you do not have to become loud to become excellent at this.