When I first started I was thrust into presenting, public speaking, board rooms etc. Sometimes by myself. I was terrified and in addition to the mental anxiety I had physical symptoms as well including shaking voice, elevated heart rate, clammy hands etc.
Over time you grow confidence in yourself, but in the beggining my doctor helped me with the physical symptoms with a perscription to propranolol. It wont take away the nervousness and it wont make you a better narator but it does help mitigate your bodys reaction, so less sweating, shaky voice etc.
I dont use it anymore but in the beginning it was my crutch.