(Bloomberg) — I wrote a column earlier this week about U.S. workers' widespread and well-founded anxiety about retirement, and how, in the absence of any meaningful public or private efforts to address those concerns, many plan to work into their 70s.

Related: Work long, live long, prosper

I proposed that this newly-contemplated fifth decade of work presents a golden opportunity to fund retirements quite cheaply — for just $16,500 per worker by my estimation — assuming that: 1) We set aside that money at the beginning of workers' careers in order to leverage the magic of 50 years of compounding returns, and 2) We invest the money in a straightforward 50-50 U.S. stock-bond portfolio.