How to overcome...

How do you overcome public speech? Presentations you have to present? Etc. I have a bad anxiety for it. My voice shake and my face turns pretty red and I can hear my heart pounding so fast, ready to jump off. But after a whole good 5 minutes, i will be more calm. That thought of going up in front of everyone and being the center of attention is frightning. Like how do some people do it so smooth and could be so brave. I wish this wasnt part of who I am.