Nervousness and the fear that comes with it is not a welcome thing for anyone who performs in public.
When you experience fear your sympathetic nervous system kicks in. Your heart rate gets faster, adrenaline kicks in, your non essential systems start to shut down ( like digestion), blood is routed away from your extremities ( your arms and legs... so you get weak in the knees). Your pupils dilate, your muscles contract. None of this is conducive to giving a motivational speech.
Over the years I have definitely experienced a lot of stage fright. Over time I just decided to embrace and exploit fear instead of hiding from it.
I think about fear as excitement. The same physiological response you have to fear, you also experience when you are elated or excited. Your heart rate speeds up, your nervous system activates, adrenaline is involved, etc, etc.
In other words, fear and excitement are almost identical. Notice that all great motivational speakers have a lot of excitement for their message. In fact, excitement is necessary to deliver a great motivational speech. Without it the delivery would be flat and lack enthusiasm.
The minute you start to think of nerves as excitement, you blossom from the contraction of fear to the engagement of elation and a stimulating speech. An excited performance is animated. A fearful performance is scary.
As a motivational speaker the audience mimics your energy. If you are happy, they are happy. If you are scared, they are scared.
The easiest way to handle stage fright is to label it as excitement. When performing, just call the energy happiness and excitement. As you embrace the experience, the nerves will quickly transform to excitement and translate into an exhilarating experience for everyone.