Why is the spirit alive?
The spirit is alive. I think of this mystery. The spirit is the same as the original person, so the brain and body of his spirit is exactly the same. His body breaks and dies. He becomes a spirit. His spirit has the broken body. But it is alive. Why?

His heart stop and he dies. His spirit separates from his body. His spirit revives from the state in which its brain and heart stop. Then, the cells of the spirit must be revive even if blood does not flow.

The spirit can work without oxygen
When the heart stops, people die with lack of oxygen. In that state the spirit wakes up. The spirit can be active even in the absence of oxygen. This is the feature of the spirit only.
The energy of the electron transfer system that uses oxygen is essential for people. The energy of cells without oxygen is either glucolysis system or citric acid cycle system. The spirit will get enough energy by those.

The spirit can live in the state human beings die. The cells of the spirit can generate enough energy in a way that does not use oxygen. It is glucolysis system or citric acid cycle system. This is the difference between humans and spirits.

People suffer in water. But the spirit does not suffer in the water without breathing. The spirit can dive for a long time. Cattle and fish spirit fillets must be fresh and alive long time.

See you.