The human body is a complicated organism, just ask anyone who studies it! It is so complex that we have experts highly trained to understand very small parts of how it functions - specialists. Yet it goes on day after day, for the most part, without any help or interference of any kind. Each system has checks and balances and is harmonious with all the other functions of the body. When looked at as a whole, both mental and physical health can be regarded as one supersystem - a term I first heard from Dr. Gabor Mate (well worth looking up on youtube). To regard the systems as separate may be necessary for the human mind to work on health problems, to comprehend them, but in truth they are all interconnected and so the holistic approach to health is always more beneficial than just pills or mechanical manipulations.
If we could model our care of Earth on our own biology, make sure that every part of human life coexisted with our planet in harmonious ways, then we would have environmental and social stability ongoing into the future. In the body we call these systems "feedback loops," in other systems they can be called "virtuous cycle." These cycles would produce some benefit or improvement as they are applied rather than deleterious or antagonistic effects, bit by bit improving the planet we all depend on and helping humanity to be healthier and happier. To do so is a huge task, given the complexity of the world in terms of food production, health care, education and societal justice - but there are billions of us, surely we can do anything we set our minds to.