I totally got to beat up my brother today

I'm taking Karate and my little brother is my instructor. Today, he instructed me to punch and kick him as hard as I could. Last time he did this, I was a bit timid (I have no desire to harm my brother) but he assured me that as a professional, he could take it. So, this time when he told me I would be doing some techniques on him, I gleefully clapped my hands and promptly let him have it – full force. I got to punch him, kick him, knee him, and flip him over. He said he'd be "feeling it" in reference to one of my punches and that he'd never been flipped so well. So.Much.Fun! Man, oh man. How did I resist this for so long? Karate rocks.