How to know when you are uncoordinated

The other day I was doing a kick boxing workout video with my 4 year old, (we actually made it all the way through without the other two waking up) and toward the end I was getting worn out. My arms began flailing instead of punching the air, my jumping got much slower, and my mind began to drift off. I was quickly snapped back into the present moment when I felt something smack me in the face. I looked around the room in shock to figure out if my son had thrown something at me, when he told me through giggles, "mama you just punched yourself in the face!"