Mental Sharpe Ratio

Investors judge a fund not by its returns alone but by its returns per unit of pain — the profit divided by the volatility endured. This ratio is worth stealing for your own decisions.

Because we usually judge choices by output only: the prestigious job, the ambitious project, the impressive commitment. We forget to divide by the turbulence. The job's salary divided by its sleepless nights; the achievement divided by the anxiety it cost; the gain divided by the variance. Some of the best-looking returns in a life are terrible on a risk-adjusted basis.

The reverse is also hidden: the modest, calm arrangement — the steady work, the quiet friendship, the walkable neighbourhood — shows unimpressive returns and magnificent ratios.

So audit your commitments like a fund manager. Which of them pays well but swings wildly? Which pays steadily and lets you sleep? You do not need to maximize return. You need to maximize return per unit of stomach lining. That is the number you will actually live with.