Let's start with the word, in two parts Qi and Gong.
The medical Classic, "The Yellow Emperor's Inner Cannon", teaches us: ‘It is from, calm, indifference, emptiness, and non-desiring that true qi arises. If the spirit is harboured inside, whence can illness arise? When the will is at rest and wishes little, when the heart is at peace and fears nothing when the body labours but does not tire, then qi flows smoothly from these states, each part follows its desires, and the whole gets everything it seeks’