We cannot exist without the intake of water, air, visual stimuli and food. Our environment is defined by our actions and output, physical and mental. Aging and deformities also belong in this category. But this, again, is a counter-productive approach. Exogenic and Endogenic pathogenesis is inseparable.
Mental states increase or decrease the susceptibility to externally induced disease.
The inside constantly interacts with the outside and is so intertwined with it that all distinctions between them are artificial and misleading. The very nature of dysfunction and sickness is highly culture-dependent. It is all a matter of statistics. If there is no dis-ease there is no disease. That the physical or mental state of a person CAN be different - does not imply that it MUST be different or even that it is desirable that it should be different.