First the bad news, and the bad news is: Once activated, chi can work against. In Dr. HH Shan article in Hong Kong Journal of Psychiatry that I mentioned previously, a case was mentioned in which "Mr A is a 44-year-old married male painter. He taught himself He Xiang Zhuang (a popular Qigong method since 1984 for the treatment of disease of the cervical vertebra)" was later attacked by a schizophrenic onset (later treated and released). It happens that I learned He Xiang Zhuang many years from a prominent master in Hong Kong, so I know something about it. This chi-kung (and there are quite few with similar practice logic) can activate a practitioner's chi quickly without much hard-work on the part of the practitioner. After each session, our teacher would lead us through a closing-sequence (rubbing one's hands together, rubbing one's face, slapping one's arms and finally rubbing one's abdomen in circular motion). through which our chi would be re-directed to our dan-tian (abdomen). According to our teacher, it would not be save if the chi was not directed back to the abdomen after practice. The reason is that chi may flow blindly around the body later.
Would it then be completely safe if one practices the closing sequence? Through my own experience and discussions with other practitioners, the answer is not a definitive yes. The reason is that sometimes when we relax, a practitioner's chi (because it has been activated) will be created automatically without one's volition. And since through the practice, chi has been trained to a rather free-flowing manner (hence its quick initial effectiveness), it might flow in all kinds of directions randomly. I believe this randomness is the cause of the any possible problem.
But the good news is: If we can initially train our chi (after activation) to flow along specific safe directions, our chi will do its work beneficial to us when we are relaxing even without thinking about it! How effective! When we are doing our daily chores, our chi will be doing work in the background.
I haven't practiced all the different kinds of chi-kung (actually not possible, because everyday new masters may create new ones!). My experience is that zhan zhuang is the best practice to safely activate chi and guide it to flow in the right directions, tai-chi is safe too, and so is microcosmic circulation of the Taoist yoga type. Of course that all depends on having a qualified teacher and/or a practitioner can understand the theory behind.
(to be continued)