Overcoming pain with spiritual will power?

The Chinese are known for this. They break iron bars with there head and 10 bricks stacked up with a thrust from there hand. I believe its called chi gong ( please correct me if i am wrong). They use there pain that they would have felt from a hit and reversing it into strong spiritual will power which in turns makes them almost resistant to pain, or negative energy so to speak. I am very curious about this fighting style, but am very ignorant on most of it. If you have any info about or any links that can inform me about it, please post them. Thanks