which exercise or routine leaves you flat out on the floor
Definetly planks. From the minute I start my whole body starts to shake, and when i'm done i'm literally flat out on the floor, I just drop! I don't sweat that much while working out for some reason, but basketball does it to me every time.
"To be a warrior is not a simple matter of wishing to be one. It is rather an endless struggle that will go on to the very last moment of our lives. Nobody is born a warrior, in exactly the same way that nobody is born an average man. We make ourselves into one or the other."-- Carlos Castaneda