"To achieve a high savings rate, start viewing your purchases in terms of units of your time rather than dollars," says J.P. Livingston of "The Money Habit," who stashed more than 70 percent of her income and built a nest egg of $2.25 million before age 30. "So instead of saying a new unlocked iPhone costs $800, you might do the math to figure out it would cost you 60 hours of work, or a week and a half of your life."
It makes you question whether any given item is really worth the money — which is to say, the effort and the time.
"This is great for big purchases," the New York City-based early retiree tells CNBC Make It. "To buy a home with an extra bedroom or one with fancier finishings might cost you $50,000 or $100,000. Is that worth working three extra years to you?"