As Marcus's knee sunk into Johns gut he coughed out all the air that had filled his lungs. That blow had been enough to throughly get his attention. He was far from giving up however. "Shut the fuck up."  he groaned. Instinctively he kicked Marcus in the shin as hard as he could with his poor footing. Then with a bent arm he swung his elbow up towards the side of Marcus's face. 
His breathing was heavy and sweat began to collect on his face and body. John regularly went to the gym to keep in good shape, but working out wasn't alone enough to prepare him for such a vigorous fight. Emotions high and inhabitants low, John would press on.