The Myth Of Health
Most of us grew up from western education. Our knowledge about health, medical, diseases symptoms and preventions are the results of scientific researchers. Researchers analysis and theories are based on a sampling of guinea pigs or a group of volunteers. From that study, we also know how to improve and maintain our health; which is a good thing.
However, there is no such health condition stay forever. If we count a seven years life period, once you reach 21yrs old your health is declined. Furthermore, each human is a unique individual with its own bio-clock, DNA, inherited genetic and metabolism. If that healthy body exists, you can find a human with age more than 120yrs old. Unfortunately, that's not possible until today.
In reality, even though someone has a good life quality such as doing regular exercises, always eating a healthy food etc., a risk to get cancer or any other diseases is still possibly happening. There is no guarantee at all that if you're following a health theory, you will achieve the same results because that theory only applies to average human conditions in general, randomly. On the other sides, the mechanism of the human body processes is a complicated relationship between body, mind, and spirit; it's a unique process that only valid for each person individually. Your medical record only gives you the report of your physical status in general.
What does exist, are the level of individual healthy mind and body where you're the one who knows about that state, mentally and physically.