Rebrand Stage Fright to Overcome It
scientificamerican.com
scientificamerican.com
In general, accepting some kind of discomfort helps the body to accept it and deal with it. I discovered this a few years ago when walking through biting cold and deciding to EXPECT the sensation and accept it. My body kicked up the temperature production, and I felt a bit like that guy who can regulate his body temperature naked in the snow. Although of course less genetically adapted than he is :)
I can contrast this with rehearsals, where I typically feel no 'excitement' when working with familiar musicians. In this situation the music might feel a little flat, and sometimes I look forward to the actual performance where the adrenaline will help carry the weight.
[1] http://www.ted.com/talks/kelly_mcgonigal_how_to_make_stress_...
If your anxiety is low but you still get tongue-tied at the start of a pitch, taking a couple minutes to stand at the front of the room before people walk in, getting accustomed to the view room from that position, can do wonders for a presentation. Even if you need to go sit back down in your chair until you're called to present, having that mental picture already familiar in your mind helps get past the shock of the unfamiliar room view.