We are fortunate that oxygen is generally abundant. We breath it into our lungs, where it is distributed through blood to all organs. Each organ collects its share and you feel healthy. Yet when visiting the Andes where air is thinner and oxygen scarce, tolerance declines, and you feel sick. Here WOB faces a new situation, how to dispense and keep tolerance (health) at its best despite low oxygen. It first sends you distress signals, asking for assistance. You feel dizzy, sick, nauseous, and have to lie down. Your muscles relax, utilize less oxygen. Their upper oxygen stream is turned down, and their tolerance declines. Which is a necessary price for maintaining oxygen supply to more sensitive organs, like brain.
Yet you decided to ignore your WOB, and start walking. Now it has to take stronger measures. Walking requires more oxygen, depriving of it, other organs and particularly the brain. Its upper oxygen stream is dangerously low, and tolerance declines. You faint and lose consciousness. Since recumbent, less blood is forced into your legs and it rushes into the brain. Now muscles relax, turning down (at last) their upper oxygen stream. More of it is diverted to the brain and you wake up. Exhausted, you remain in bed.
After WOB achieved its first objective it raises oxygen throughput to organs. You breathe faster, heart rate goes up and it pumps more blood per minute. You cannot breath too fast, since it would divert too much oxygen to breathing muscles, and brain would suffer. WOB continually adjusts breathing and heart rate, so as to maximize tolerance (health) under the circumstances.
This example illustrates process interleaving during shortage of vital a substance. Some measures, like putting the patient to bed are undertaken also by the physician. But the fine tuning of resource distribution is done by WOB. Still, since WOB only maintains it is up to the physician to decide how long the patient will stay in bed. If kept too long, WOB might faithfully reduce bone and muscles, like it has done to astronauts. The physician has to treat in concord with WOB, to maximize tolerance.