In this book, old people on earth can volunteer for military service in space. Those that volunteer end up getting their consciousness transferred to a new bod

In this book, old people on earth can volunteer for military service in space. Those that volunteer end up getting their consciousness transferred to a new body, and effectively start a new life. https://en.wikipedia.org/wiki/Old_Man%27s_War https://en.wikipedia.org/wiki/Old_Man%27s_War