It is similar in mind over matter. Complete concentration is needed to counteract the pain that is felt. I'm half Filipino Chinese, most people do not know the real meaning of Kung Fu. They think Kung Fu is a martial art. But the real meaning of Kung Fu is "SKILLS".
So sometimes you will hear a question like this. "how is your Kung Fu"? This means they ask about your skills or abilities of your attack and defense. But the famous in Kung Fu was the TAI CHI. I am so rusty in Wushu and Jitkundo. I never use or train my self for almost 2 years.