Foundation. What is it? How do we build it? Foundation training is the single most important key to success for Taoist internal alchemy (neidan), and any form of qigong and neigong practice. Online program at https://online.nathanbrine.com/
Book series-- The Taoist Alchemy of Wang Liping
https://www.amazon.com/Taoist-Alchemy-Wang-Liping-One/dp/1777046807/ref=tmm_pap_swatch_0?_encoding=UTF8&qid=1605827568&sr=8-1