Guarding the three treasures is the goal of Traditional Chinese Medicine, Tai Chi and Qigong practice.
Essence known as Jing in Mandarin is collectively referring to every fluid and hormone in us.
Energy known as Chi in Mandarin refers to vitality which arrives when we have abundant hormones and our blood, lymph and other fluids are clear.
Spirit or Shen refers to mood. Many people believe that the spirit referred to here is a profound trip into an inner world similar to drugs. This IS NOT the case.
The practices collectively referred to as Qigong develop the body and stimulate the secretion of hormones and the practice further regulates the endocrine system escalating the production of hormones, plasma, bile, lymph, digestive juices etc. This leads to a body that functions at an improved level enjoying elevated levels of vitality and fitness.
Having more energy and a body that moves with the agility and endurance of a child is bound to make anyone's day hence the subsequent elevation in mood is what is referred to as Shen or spirit. Nothing more, no mysticism although the practice of Qigong and Tai Chi will make you feel like your world just became very interesting. Do this right and it is a blessing, wrong, a curse.
The Chinese have developed systematic practice protocols based on thousands of years of meticulously recorded research and although superficially the practices may appear simple but in reality are activating deeper layers of our being and bring more of us into life.
There is good reason that these practices enjoy such a reputation. Millions of people do this daily.