Don’t get discouraged if singing doesn’t give you immediate results. It takes awhile to develop those muscles. Uuuhm in my experience if i have to give a presentation at work or something along those lines I speak in more of an authoritarian sort of voice which is slightly louder but not yelling. Idk why but i feel more relaxed and more confident which allows me to speak more fluently. That’s my own personal experience. I’m not sure if there’s a scientific reasoning for that.