Most important today is the part of Qi Gong that was developed for improving strength of body, mind and spirit.
Qi Gong for health is founded on empiricism, or experience, trying what worked and what did not. Qi Gong is not based on superstition.
Qi Gong was used by ancient Chinese warriors as a lifelong preparation for battle—preparing the mind, body and spirit for the conditions and demands of combat.
For the warrior fortunate enough to return from combat, Qi Gong had many remedies for the physical, mental and emotional injuries that occurred while fighting.
At the esoteric level, Qi Gong is about finding the strength of our immortal self, and expressing this strength in our active daily lives.
Many Qi Gong Masters have been reported to live to surprising ages of 180 years or more. Some Masters have been described as immortals, so developed that they were untouched by destructive and aging influences of the world.