Some moments are worse than others for everyone, regardless of age. Given too much exertion, there are times when one is out of breath with heart pounding and legs weak. That has no age limit. And, when such happens, if it’s bad enough, almost anyone, just on that, might reflect on dying. Police, fire department personnel and many other occupations both noble and rather ordinary (some of the latter are store clerks, those who drive some kind of vehicle for a living and electricians) often do more than reflect.
Some people don’t want to think about dying, even though it’s sure to happen. It’s a complete unknown regardless of scientific study and/or religious speculation. Really considered with what’s known, it carries a notion of total nothing, as total as before one was born. It involves much pain. Even among those that operate in knowingly dangerous situations, there’s a good chance it will be unexpected. (If it could be foreseen, those that know precautions would be able to avoid it.) It involves other things as well.
While it can’t be planned out under ordinary circumstances, how a person hopes to die is a legitimate question. It probably won’t be that way at all; but, one can hope it is more one way than another and maybe even live so that it can more likely be in one way rather than some other. Some want to go out heroic, while in the line of fire but simply overwhelmed. Then there’s the utterly placed way (maybe) of just going to sleep one night and not waking up again in the morning.
The future is never sure.