The basis of Qigong

Has anyone on here ever studied Qigong?  I have always been under the impression that it is just a martial art, but never realized how many different elements go into making Qigong what it is.  Apparently, Qigong focuses not only on the martial arts aspect, but healing and happiness through the four bases of Qigong.  The four bases are martial arts, shamanism, spirituality, and medicine.  This is also a very cost-effective method of treatment, because "the only investment you need is time, just a half hour to an hour a day" (Cohen).  Has anyone ever studied the art of Qigong?  Is it just like a hobby like yoga or something?  Or is this an art that needs the devotion of your life to achieve what you are wanting from it?