How To Stop Leg From Shaking Nervous I Don't Feel Nervous, Yet I Still Shake. Any Ideas How To Stop This?

I don't feel nervous, yet I still shake. Any ideas how to stop this? - how to stop leg from shaking nervous

I am a leader, and every single home game of basketball, boys and girls, my coach asked me to sing the national anthem. I'm going to do, and I'm not nervous at all. I'm not at all, because I very often. Also, I am in my music and the school choir and solo singing, so I'm not nervous in general. But that's the problem:

I began to sing and immediately starts shaking like crazy! My hands were shaking and my legs were shaking and his voice makes me tremble in the upper parts of the song. It is really annoying. All suggestions as to how the assistance will be welcome to shake.