I get anxious if I have a plan. If I just wing it, I can talk in front of people forever. I hate powerpoint presentations for exactly this reason; I stand up there and stress about looking like a handicap reading off the screen. But if I did that same powerpoint presentation off hand without any slides, I'd wreck it with no stress. I always get better grades when I do that because I actually interact with the audience and stuff instead of just sitting there like a zombie reading the slides.