Thanks so much this is very interesting. I have always been curious about this.
I would be useful to add D(A) = Exp( Age of Death | Your current age is A).
D(A)-A then would be the number of years you have left to live.
$40,000 * (D(A)-A) would then the expect amount for you to spend (assuming $40,000 a year).
Some sort of risk analysis. How much would I need if the probability I run out is at most 5%.
Thanks