Microcosmic circulation (小周天) is the foundation practice of Taoist meditation. Its relevancy cannot be overstated. One may wonder, if I'm not going to do Taoist meditation, how can it be relevant to me?
It will be relevant to anyone who is doing meditation to any degree of seriousness, in particular one who does so without the daily supervisor of a teacher, which is probably true for most meditators. One takes a few lessons of meditation from a teacher and off one goes. I mean if you do it seriously, one day you might encounter situations in which powerful chi might, without any intention from you, be generated in your body. And without a proper conscious guidance by you, chi might rushes aimlessly and might become stuck in certain area(s) in your body, and worse yet, it might affect your brain causing disturbing hallucinations. Chi-kung or kundalini syndrome.
As we can read about these disturbing, sometimes fearsome, experience even from the biographies of some self-learners who later successfully managed these disturbing powerful chi and who later turned out to become teachers of the stuff. I'm sure many of these self-learned gurus have later found their own way to avoid the disturbing experience.
How should today's self-learners proceed with the necessary preparation and precaution? I think the best way will include learning how to do microcosmic circulation. The objective of doing that is to open the chi channels up one's spinal cord and down the front of one's torso, ending at one's abdomen where the power of the powerful chi can be under one's conscious control. Initially, one doesn't need to build too strong a chi to open so thoroughly cleared a path. The reason is that as long as some form of cleared path is opened (and maintained to be opened through regular practice), one can always use it to channel any powerful chi that might suddenly comes it way during one's meditation - without any fore-warning.