This guy is truly amazing, and I've done some research on him and he actually seems very credible. There are obviously a lot of charlatans in this field, but John Chang enjoys the respect of a lot of well informed people. I'm a noob here so this may have been posted before, but if you haven't come across him before I suggest you at the very least check out this video clip:
http://www.youtube.com/watch?v=Aos0hnwiHt8It certainly didn't ruin my motivation to practice Qigong....
)! I had not come across him before and I thank you for posting this link.