Much has been written about the need to invest when we are young, and how having a longer investment horizon lets us invest in riskier stocks in order to achieve returns higher than inflation over a 30 to 40 year period when we are working. But with longer lifespans, we will spend almost as long in retirement as we will working. And because we no longer have a steady income from work when retired, how do we know if we still have enough to last for the rest of retirement? This is even more critical for the early retirees: How do we know if we are running out of steam while on FIRE?

So far, we have posted quite a bit on how to drawdown on the investment portfolio during retirement, i.e. the Safe Withdrawal Rate:

All this tells us how to start off our retirement, how much to