The article discusses this. In part: > Americans cannot imagine stopping work before they've either (1) purchased everything that they could conceivably want,

The article discusses this. In part: > Americans cannot imagine stopping work before they've either (1) purchased everything that they could conceivably want, or (2) collapsed from physical exhaustion. If your material needs and desires are sufficiently low, and your resources sufficiently high, you could retire. Age or usefulness to an employer could be an upper bound, I suppose. I look at it like this: finances are like a bathtub. What you spend is the drain, your income (whether salary, interest, cap gains, etc) is the faucet, and your resources are the water in the tub. Retirement is the point where you can turn off (or turn down) the faucet and not run dry. Some people have big drainpipes and need a big tub and lots of water; others can live with a trickle.