It has been one of the biggest obstacles in acting for a long time. Stage fright sucks, because it robs you of a lot of qualities. First lets look at what it is. To me it is when an actor intraverts before, during or after his performance. The artist simply cannot concentrate on what he/ his character is to be doing and becomes solely focused on what he (the actor) is doing, looking like, sounding, appearing, what everyone is thinking etc.
What soon ensues is a case of nerves and to many different degrees anxiety. So how does one overcome anxiety and replace it with confidence, ability, creativity? This is what I suggest you do, freak out. Just let that shit happen. Whoa whoa, who is this guys, what is this all about, you ask? Let me fill you in on what is really going down with stage fright.
You can only feel one emotion at a time. What most actors do when the feel nervous is try and suppress it. That is your 1st mistake. Anxiety is energy, that same energy you cry with, rage with, and laugh with. It is just that at this point in your career you are feeling nervous. And to be totally honest who cares? Pretty much you and only you. I audition people all the time, and yes they are visibly nervous. I see it, casting people see it, agents see it. Just chill it is nothing to be ashamed of. This is the actors first major mistake.
Feel the nerves and let it show, feel it and say your lines, just let the feeling happen. Get comfortable feeling nervous. As an actor you have to get comfortable feeling and feeling strong emotions and staying focused. Focused enough to follow your blocking, to work with the camera, find your light, say your lines, etc. It is a high wire act, if you try to suppress your emotions and play another emotion over top of it, it will come off as forced and unreal. Quit doing that, no one is buying it so quit trying to sell it.
Once you can actually feel anxiety and release it you will be able then to do other personalizations or sense memories. Those awkward emotions will eventually fade. When that time comes, after much practice for some, you can then connect to your energy again and direct it as you see fit. It can be channeled into what ever emotion you chose. Now you can be accessing all of that brilliant creativity.
In summary stage fright is you doing a personalization of you failing. Knock that off! It doesn’t help you with your objective, being a working actor.