The endocrine imperative.

The endocrine system makes decisions based on your bodies reaction to the outside world.
The minute adjustments needed to optimize function. And large decisions as to whether you are in a position to procreate.

I believe that if the body feels that you or your situation have in the long term,  no chance to make a copy, then you will be taken off the board. This is not a hard and fast rule for humanity as a whole, but for most it is.

For certain Monks who spend each day in a meditative state. Who are sensitive to their body's deepest workings, they might be exempt by transcendence from nature. Their goal is to leave earthly concerns and concentrate on heavenly ones.

These people are not likely to need this essay.

The first step is to examine your situation to see what might be the reactions your endocrine computer is observing and has been observing.
Are all parameters stable? What is the food situation? Are you repeatedly stressing your body by frequent and long exertions? Are you experiencing high internal stress with no exertions? Are you exposed to pheromones from a fertile individual of the opposite sex? Is such a person aroused around you?
Your endocrine system observes the reaction markers posted in your blood, and makes an overall decision as to whether you stay or go.

Generally the endocrine system will not be hasty to remove you in your youth, but as one becomes older...

There are many forms of transcendence.  All we are exploring here is an overview of the system and how we can order our environment to send optimal signals to our endocrine computer that gives us permission to stay.

Studies say that a person who lives alone, with few interactions,  have high mortality rates. Their happiness with their lifestyle is not a factor.  50 years of insurance statistics bear this out. This is why singles pay more.

The point in time one knows that the kill switch has been thrown is when the sex organs begin to fail. Once that occurs it's real hard to come back to a youthful state. If this happens in a woman when she is young it's called Premature Ovary Failure. A little later it's called Early Menopause.  Later still, Menopause.

In men the word is Andropause.  True Andropause is not just erectile dysfunction.  It's depression, listlessness,  tiredness. HRT (Hormone Replacement Therapy) in men is very dangerous. There was a clinic in the US that specialized in HRT wide spectrum replacement. It was very pricey.  They have disappeared from the in flight magazine's,  because all the doctors were users and they are all dead. Then the estates were sued until all assets were distributed to the plaintiffs.

If one has a detailed understanding of their body, and they begin to practice correct behaviors with placement in an endocrine supportive setting, the kill switch might never quite be thrown. That's not a pass for eternal life, just a vital long one.