Because there is so much discussion on this board about the small heavenly orbit, I want to share some knowledge from the classics here in order to clarify some things.   I'm going to do the first part of the post in point form and then elaborate on somet things as need be:   - the MCO of Daoism represents a small version of the universe which is contained in the human body.  The Da Zhou Tian, or great heavenly orbit in Daoism is the actual universe. - the small heavenly orbit in Qi gong more specifically means the connections between the Du Mai in the spine and Ren mai in the front of the body.  The big heavenly orbit in Qigong is the whole body. - When we want to open our Du mai and ren mai (because this is what most MCO threads are talking about) we have to decide whether we want to use post or pre birth Qi. - if we are using post birth Qi, such as with Qi gong practice, it will take much longer to open the orbit, but it can be done in coordination with physical exercises and intention. - if we want to open it with pre heaven Qi, we have to accomplish this through "action without action," and it can only be done through silent meditation. - it is most common to be able to do a superficial orbit of these meridians, but that doesn't mean that they are open, it just means that you can either send some post birth qi, or pre birth jing around the orbit, depending what type of exercise you are doing. - a deeper opening of the dumai and ren mai accompanies all kinds of physical symptoms such as "he che," the water wheel, or the movement of the perenium and so on.   I want to touch on the most important aspects in a bit more detail. When we want to open the du mai and ren mai, we have to be aware of the method we are using to do this.  Doing Qi Gong can have an effect on these parts of the body, but to really open them deeply will require many years of effort.  Qi gong will also only work with post birth qi, which means that even though we can move Qi through the orbit, it will only be related to breathing, blood flow, and intention, rather than opening the yang gate and so on, which is more associated with Daost practice. If we meditate, we have to be aware that Qi moves sponteneously in Nei Dan and that this isn't something which can be put under our conscious control.  We have to adopt the mind set of no mind, the posture of no posture, and learn to gradually forget the breathing. This is actually a much easier and faster process than Qi gong, but it also requires more theoretical knowledge to do correctly. If you want to open your MCO through meditation, the first thing you have to learn to do is successfully hide your intention in your dantian.   This hiding of intention involves places the mind in the LDT, leaving it there and not letting it rise up the front of the body.   It can take several days to several years for the intention to begin moving Qi, but most people can experience this within a few weeks, at least in a superficial way.   Sometimes people get the symptoms of meditation confused with the practice, and I want to expressly state here that: - contraction of the testicles, perinium and stomach are natural symptoms of the yin qiao meridian opening and are not things which you should intentionally practice. - clenching the anus during meditation is incorrect practice, since it will disable you from achieving genuine non action. - when things like the anus and testicles naturally move, this is called "he che," or the water wheel, and is simply a symptom of Qi beginning to do stuff.  Don't try to augment it in any way. - leaving the anus relaxed will not cause Qi to leak.  Qi leaks through thinking perverse thoughts, speaking excessively, eating poisoined foods, having negative emotions and so on. The anus is composed of two sphincter, one on the outside is somewhat relaxed, but the one inside is always tight unless you are deficating.  You don't need to worry about your anus while meditating. - the reason why martial arts and qi gong people tighten the anus is actually to support the abdominal floor in order to stabilize their physical practice during movement.  Meditation doesn't move, it doesn't require this.   Usually the Du mai will open first and the qi will pass the three gates (wei lu, jia ji, yu zhen) and make it to the head.   At this point, the Qi will fall down naturally when it is ready to.  If you want to control it a bit, you can gradually move it through your three dantian.  It is better to do this with as little intention as possible.  In the end, the du mai and ren mai should open naturally and without effort.  The Qi should just go there and you should simply be present for it.  These are natural pathways in the body and can work by themselves and without outside help.   If you find that your Qi won't go to your Du Mai, you can "chong Qi," or purposefully slightly move your intention deeper into your dantian.  The idea is you should relax and then relax again, return the mind to the dantian, and then return the mind again.  This constant returning and relaxing will help you Qi move better.     Remember in the long run that this is less about moving Qi and more about cleaning your body and mind of obstructions.  If the Qi is healthy, it will move naturally, and you should be aiming to be healthy.