Health is important, but hard to define. Some people go by their idea of normal function or appearance; in any case, the idea seems to be that health is required to satisfy one's desires, whatever form they may take (functions, motions, emotions, experiences, etc.). Since some desires are considered by societies to be taboo, the situation is a bit more complicated.
My people, Americans, of course, speak mostly of individual health. I hear from all corners of America that society is sick, but there's clearly no consensus on what this sickness is; often side A thinks the fault is side B and vice verse.
My proposal is that health be defined for anything that can be understood as alive (even if only partially). Any self-proclaimed environmentalist should agree that our planet seems sick; it's reasonable that we have an idea of planetary health. The story we have is that a few thousand years ago, it was only humans (in some places) that were sick. Most of everything else still ran well, comparitively.
Throughout the Earth's history, we believe the planet assumed many climates and ecological forms. Finding remants of old organisms still fascinates us and excites the imagination. Since the system and its history are so much larger than individual humans can cope with, it is far more difficult to define "absolute health" than "relative health." So for now, considering only relativity, we need only concern ourselves with what changes health.
Any attempt to improve the health of an animal, plant, society, or planet obviously must seek some goals. In this spirit, I propose a more or less mathematical definition.
We must understand ourselves as partaking in the vastly complex process which is the living film surrounding the rocky earth. The atmosphere often serves to bind the biosphere together; without a nice big cushion of air, plants and animals couldn't cycle air.
I call a being in such a situation a tangle, since it realizes itself and its actions as tangled up in as many planetary cycles as it has active consituents (air, water, carbon, energy in photons/electrons, etc.). Here I refer to a chemical understanding of the body, but I believe any unit of any 'scale' could be used.
Insofar as a tangle can content (stabilize? fulfill? re-secure?) itself in the environment with which it is tangled, it can think of itself as healthy. I just leave it up to any tangle reading this to define its own contentment. Some distinct alterations in lifestyle may be adapted to adequately that no distinct difference in health can be noticed. In fact, there may be apparent many such configurations accessible from any given configuration.
It's reasonable to assume that any healthy configuration becomes understood as a norm after some time, such that with increasing normalness, more subtle variations from the norm can be deteced. So deviation from a given norm doesn't necessarily indicate movement towards ill health.
As one more fully understands the extent to which one is tangled with other accessible systems, one may see one's individual health as related to wider communities' healths. The connection is most clear when an other community member's processes are understood as being in series with one's own organismic processes. In such cooperative circumstances, slowing down the other's processing potentially limits one's own health.
One way to decrease health, then, is to disrupt a cycle by processing its elements in a way that limit other life's access to them. Discarded plastics are a good example of this.
If one understands a border between two systems in series, one can affect health by changing the physiology of the border. Clogging vital tubes is an easy example of this. If you were to block the pipes of a house or the arteries of an animal, you'd soon notices drastic changes.
Weakening or destroying systems you cooperate with is by definition unhealthy.
In human societies, killing friends might be a way of reducing one's own health, if those friends helped in some vital process (not to mention any guilt and community responses). Even if one learns to fill their old roles, it will take more time for one to do the tasks of many. Should other vital tasks pop up, the increased time requirement may leave one stretched to thin, relying to much on wearing pharmacodynamics or other tension, possibly reducing health. Is there some equilibrium point, given a situation? I don't know - but don't work too hard on the problem.
Hurting people to the extent that they refuse to cooperate with you is often unhealthy. If the situation goes without remedy, such wounds may fester and reduce future health.
Though complete control of the biosphere necessarily eludes humans (being as we are only a small portion of the total process), we can imagine as an ideal a complete understanding of every cycle you and I take part in. Remember that some cycles might be expected to take many millions of years longer than humans will survive. In actuality, some of them perhaps aren't exactly cycles given a time frame of even billions of years; perhaps some atoms belonging to you will end up in outer space or deep within the planet, only to emerge long after life has extinguished. It's impossible to say. However, we can expect that a substantial portion of the atoms that constitute Terran life would look cyclic if you could only get enough info. Another option to think about "non-cycles" is to just "black out" the non-living parts of the world, leaving it unspoken of, so that such material "disappears." This is actually a more accurate picture of a "cycle" (as I'm using the word) than a perfect circle - there should be some fuzzy dark part to denote our uncertainty of the total cosmos - indeed of any process we take part in.
The total amount of you or me expected to be in cycles vs. non-cycles, then, is either a matter of quantitative analysis/estimate, or somewhat irrelevant, depending on your goals. (I'd be very interested to hear any number you might come up with - this may begin to give us an idea of what "absolute health" could mean.)
Consider the food you eat, and any other materials required to sequester its nutrients and energy. Where will your waste go? Will it be mixed with the ocean and atmosphere? Even if a certain constituent couldn't be observed to cycle in any lifetime, it at least came from somewhere in the non-living cosmos and went back, perhaps to return some day. The faster a body like yours is able to access its re-processed waste, the more bodies like yours can live healthily at once; the more fuel flowing, the hotter the fire.
Perhaps an eco-utopian gola, then, would be to configure our current species to cooperate as smoothly as possible. This "optimal health" would be a bit like a Nash equilibrium: no change in lifestyle could lead to greater health for everyone. What if there is a whole spectrum of such configurations? It would come down to preference.
If you live on an organic farm (depending on type/schema), you may have a very good idea of where most of your waste will end up: cycling back into yourself and allied humans. Humans can be fickle, of course.
Mine is a non-deterministic understanding of life, which has yielded a non-deterministic understanding of health. Being more an aspect of a continuing lifestyle than any one moment of that life, understanding our own health guides us, but this understanding being non-determining, it does not rule us. The rate of addiction in America proves it; we get into unhealthy situations more or less willingly (though not necessarily knowingly). Note that this can be understood from many addicts' own viewpoints: admitting you have a problem is a first step to recovery. Something about the lifestyle they've gotten into isn't working for them any more. This is an illustration of how "health" need not refer to any norm - rather only a relative judgment of how desirable a situation is.
It seems that health is necessarily sustainable, but not identical with stability or predictability.
These ideas are still somewhat in experimental stages. I am interested to hear questions or critiques.