One day, years ago, while working as an attorney at a large local law firm, the partner on a case glanced at her office door to make sure it was shut, then said in a hushed tone, “I’d accept a twenty percent pay cut to work even a half day less around here.”

It was a surprising admission from one of the leading partners in the firm, and I was flattered that she would bring me into her confidence. But when I asked why she didn’t go ahead and do that, she looked at me as if I’d suggested something preposterous. Settling back further in her chair, she stared at me for several moments as if contemplating the question of my own loyalty to the firm.

I thought of the incident last week when I read about an attorney in D.C., who, 50 years old and at the top of his profession and career, suddenly quit. Partner at a large Chicago law firm for two decades; co-founder of a prestigious 40-attorney litigation boutique that he managed. Professionally, he had it all, but the rest of his life suffered as he worked weekends and on vacation, neglecting his family.

That’s the way it seems to be in 21st-century America - you’re either on the bus or off, as far as work is concerned. For ambitious, hard-working people, education leads to full-time employment then to a retirement full of . . . something. It’s a 25-40-25 model, reflecting, roughly, the number of years spent in three distinct periods of life. Like all models, it doesn’t fully capture the messy reality, but since WWII, it’s been the ideal to which many people subscribe in organizing their lives.

Ninety years later, it looks like Keynes hit a bullseye with his productivity forecast. But the three-hour workday? It’s nowhere in sight. Despite more than half a century of ever-increasing productivity, we’ve continued to work about forty hours a week. Why?

Economists studying the issue find it easy to explain behavior at the extremes of the economic ladder. At the lower rungs, people often work two or three jobs to make ends meet and fear working too few hours, not too many. At the upper end, passionate workaholics -- often successful business owners -- work long hours because they love their jobs, are well-compensated, and can’t imagine doing anything else.

For everyone else, the persistence of the forty-hour week is harder to explain. Their work is tolerable, sometimes even enjoyable, but they have other interests that they could pursue if they worked less. Theoretically, they could put bread on the table by working only half the week, but choose to work the other half as well.

There are other reasons for why we may choose work over other activities - social connection at the workplace; a sense of self-worth or identity -- but presumably we would not have to give these things up if we merely reduced the hours worked rather than quit altogether. Perhaps there’s something deeper at work.

Those concerns make sense, but how much do they apply where we’re only talking about a decrease in hours worked and not an elimination of jobs altogether? There’s quite a bit of evidence, as it turns out, that working less enhances our happiness, rather than filling us with existential dread.

Fortunately, we’ve begun to see employers experiment with reduced work hours. A paddleboard manufacturer in San Diego implemented a 5-hour work day several years ago. Its example helped persuade a German consulting firm to do the same.

There’s evidence, moreover, that working fewer hours can actually boost productivity:

If these efforts spread, it will be interesting to see how they affect the concept of retirement itself. As we continue to live longer lives, and as the advance guard of the baby boomers reports back on their level of satisfaction during retirement, we may want to reconsider the current model of backloading so much of our life’s leisure to its later stages and start figuring out how to pull more of it forward.