Lady Amy has been her slave for almost two hours. You can see because the idiot is clearly exhausted. But the Mistress doesn't care. She squeezes the air from his lungs, tormenting him with a massive reduction in his ability to beathe. She has fun deciding when and for how long he's allowed air. Until then she presses her hands over his mouth and nose. How hard do you think she would be on you? You would be as hopeless as this slave!