The title of this post is a fundamental premise of how I look at health. It's based upon this assumption: Life only perpetuates life. It does this in 2 ways, life protects itself or it seeks to grow itself.
Ultimately I believe that all expressions of health, or illness, is in someway the intelligence of the life within us either protecting or growing itself.
Nature would not select for any function devoid of evolutionary benefit. If the body can do it, it exists in service of life.