Are You The Worst Enemy of Your Business?

My 14 year old son attends classes at a martial arts center. The martial arts center is run by a 30 year old man. He is by all means a successful business man for his young age. He stood in front of his class and asked them if they knew what the most powerful muscle is in their body was. There was not an answer. My thought was he would say your brain. When the 10 year old in front of me popped up and said