Chomping at the bit

I have had little experience with horses.  The horse I was given at a riding stable in Britain tried to roll over on his back with me in the saddle.  If I hadn’t dismounted as he went down, he would have pinned beneath his weight.  As I recall now, our guide said something like “Oh he will do that now and then.”  

I realize that virtually everybody once depended on horses for transportation, as well as breeding and racing and plowing.  

When I can feel internal eagerness for something, I sometimes think I am “chomping at the bit”.  I looked the expression up and found it was once “champing at the bit”, that is, biting onto the metal bar that passes through the horse’s mouth as part of the gear used to guide the horse.  I have never bitten repeatedly on a metal bar, but I sometimes do feel I wish time would move along since I am ready and energized and eager.