Old dude, c'mon! I know you're stressed, buy try a little tact and persuation.

As in:

"Of course you're not dead yet, and your mind is perfectly fine. But your eyes are letting you down. You're 82, and the eye doctor says you can't see as well as you used to. And your nerves are letting you down some, too. Your reaction time is getting slower. Meanwhile, today's kids drive so wild, some of them on their cell phones so they don't even have their cars under control.

We don't want you getting hurt."
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Keep in mind that when "they" take an old person's keys away, "they" seem to be saying "You are a useless, senile piece of junk!" Don't seem to be doing that yourself.