The first thing many people think about when they think "wellness" may be related to food, diet, nutrition, and exercise. "Proper" consumption is exceptional for maintaing wellness without ever undestanding diagnostics.
Others may first think about Yoga, Mediation, Self-Hypnosis and the Martial Arts. All of these are EXCEPTIONAL for balancing physical, mental, emotional and spiritual properties, without ever understanding diagnostics.
Others may think first about Acupuncture, Chiropractic and Clinical Nutrition. Others may get into the study of Hormones or Homeopathy.
Some who think deeper will get into "antagonists" that challenge wellness in a very biologicals sense. Those include bacteria, parasites, yeast, mold, fungus and viruses*. Note: Viruses are the only item in this group that are not a "living organism". For now, think of viral problems as being "process problems" with cell creation , management and elimination. In that regard, "cancers" are actually viruses. Viruses, are likely far more like computer viruses than most consider them to be now. When doctors say you have a virus, think of it as if you have a cell reproduction problem, which is something that will fix itself or something to be fixed. Ironically, that which makes you feel ill may NOT be from the cell preproduction problem directly. It may be from chemicals the body is creating to fix the problem. Fixing it may involve killing cells, but you aren't "killing the virus" you are removing the process problem from your body.
But what about the non biologicals antagonists? Like dysfunctional thought patterns? Emotional traumas? Conflicts between religious and spiritual ideologies or ideas about dishwasher loading with your spouse? And what about Technology and the Stress from Money, Money Management and Occupational challenges? Could they lead to biological disfunctions too?