Tansfer more and more of yourself into another (maybe) digital substrait. As your self declines more and more of it is compensated by the digital clone. Until you fade away completly. Think of having dementia. You fade away every day. Without a clone you are still your self, but shrunken. If you would have written a book and have people which remember you healthy, some parts of your self are preserved and safe from the illness. There are many ways to back up yourself, some better some worse. Currently all are passive, but you could transfer youself into a computer program, which can be active by itself and passes the Personal Turing Test. The program will pass it per definition at some point. A program, which would never return anything has the same response as if you were dead. Optimize from here, up to the reverse decline.