Ok guys I did some research
Chi (qi) is the life force of the cosmos or the cosmic life force. The cosmos is the result of two opposites (yin and yang) in dynamic interplay. When these two opposites are in harmony

they create and give off Chi (qi).
When these two opposites (yin and yang) are in harmony within a living thing, then the cosmic life force (chi or qi) that is the result of/generated by the two sides/opposites (yin and yang) of the cosmos being in harmony becomes also the life force of that living thing

and that living thing is healthy!
So the only way that one can prove that the yin and yang are real is to disrupt the harmony of these two opposites of a living thing and see what starts to decay. And that is the princibles that the marshal arts that are based on Daoism (tai chi), are based on

.
Acupuncture restores balance and tai chi as a marshal arts system screws with the balance. Kind of the opposite of acupuncture
Guys playing with chi (qi) is fun!
love,
sunny