MIT professor of Communications. Has excellent videos and writings about communication and the value of public speaking.
Your success in life will be determined largely by your ability to speak, your ability to write, and the quality of your ideas, in that order.
References
https://www.inc.com/justin-bariso/emotional-intelligence-mit-patrick-winston-how-to-communicate-effectively-how-to-write.html
How To Speak (YouTube)