When Seung Yu Chun was injured by a Mongolian warrior, the young Cheung Mo Gei saved Seung's life by using the meager knowledge of acupuncture he had gained from reading Dr. Wu Ching Ngau's medical texts. Although Cheung saved Seung from an immediate death, Cheung's amateurish and errant use of acupuncture caused Seung to lose forty years off of his eighty-year life expectancy. Indeed, Seung Yu Chun died of illness at forty, just as Wu Ching Ngau had prognosticated.
I wonder, however: could Cheung Mo Gei have given Seung Yu Chun at least some of his years back by teaching him the 9 Yeung Jen Ging? Training in advanced inner power techniques sometimes seems to produce the side effect of extending longevity (hence, the reason that most of the Greats lived far beyond the average life expectancy of people in pre-modern China). Perhaps training in the 9 Yeung Jen Ging might have enabled Seung Yu Chun to prolong his life for a decade, if not his original full eighty years?