My branch of chi kung originated in shaolin, the story that was related to me is as follows:
It began with the yi jin ching or "muscle tendon change"-this is what damo taught the monks of shaolin in order to keep them healthy enough to stay awake through their spiritual training (they routinely fell asleep during meditation, due to unhealthy lifestyles).
I study a medical chi kung of shaolin called jin gong tzu li gong under sifu Angela Yan. It is based heavily on the chinese zodiac. It includes most notably stake standing, which is the practice of adopting a specific pose for a prolonged period of time (much like stance training of most martial arts), breathing techniques incorporated with simple repetitive movements and mental visualization/ meditation, and what is known as "keigel" exercizes in the western world. The techniques are to be practiced on a cyclical timeline in accordance to the chinese zodiac (certain methods are trained in september, certain ones for october, etc. these are further broken down into smaller weekly subdivisions as well).
I highly reccomend that you do NOT practice any type of chi kung from a book, you could do more harm than good to yourself.