Aesop’s fables are shorter than I thought, given the length of their derivatives. Townsend’s translation of The Ants and the Grasshopper is only 80 words, but A Bug’s Life is 95 minutes. My version of The Tortoise and the Hare is more than six times longer than the original.

The Hen and the Golden Eggs is usually told pretty true, though we frequently substitute a goose for the hen. As Townsend’s translation tells it:

A COTTAGER and his wife had a Hen that laid a golden egg every day. They supposed that the Hen must contain a great lump of gold in its inside, and in order to get the gold, they killed it. Having done so, they found to their surprise that the Hen differed in no respect from their other hens. The foolish pair, thus hoping to become rich all at once, deprived themselves of the gain of which they were assured day by day.

The fable is a cautionary tale against unprofitable action motivated by greed. Financially, I interpret the moral as “don’t spend your investment capital”. In general, it’s a lesson in how short-term gains can come at a great long-term price.

A hen only produces one egg at a time. Eggs are laid as soon as they’re ready. I don’t know how many eggs’ worth of gold the cottager and his wife were expecting to find in that lump, but it was a short-sighted decision.

Even if they found a reasonable week’s worth of egg-gold in the hen, they still could have just waited a week and had the same gold in hand—plus the golden-egg-laying hen. It’s already a magic hen, so let’s call it immortal, too. They could have had a golden egg every day for the rest of their lives. Instead, they had an expensive chicken dinner.

We’re not magical hens, but we have to avoid making the cottagers’ mistake. Dr. Stephen R. Covey refers to this as the P/PC balance: the Production of current work vs. the Production Capacity for future work.

Henry Ford standardized the industry (and the world, really) on an eight-hour workday. Let’s define the amount of work you accomplish in an eight-hour day as “1 Ford”.

If you work an eight-hour day, you produce 1 Ford of work. Work a fraction of a day and you produce a fraction of a Ford. Makes sense, right?

It’s tempting to think that it scales up, but it doesn’t. Studies have shown that burning the midnight oil produces quickly diminishing returns. If you work a twelve-hour day, you only have 30 minutes of productive work more than a nine-hour day. That’s just 0.0625 Fords for an extra 3 hours of effort!

It gets worse because the effects are cumulative. A study by Jack Nevison of Oak Associates showed that once you pass 40 hours in a week (a sustainable rate of 5 Fords per week), the number of productive hours in the week actually drops. Employees who regularly put in 60-hour weeks are only producing 4 Fords per week.

Let that sink in. By the time you factor in mistakes, re-work, fatigue, and presenteeism (showing up to work when you really shouldn’t), someone who puts in 60-hour weeks hasn’t gotten any more done than someone who puts in 30. They aren’t more productive, just busy and stressed. Combine Nevison’s work with the 80/20 rule and there’s a good argument for a four-day workweek.

I used to work long hours constantly. I’ve put in 70-, 80-, 90-hour weeks. I’d look for opportunities and excuses to put in long hours. I was addicted to checking off boxes.

I used to get sick a lot more, too.

Productivity is a marathon, not a sprint. The race goes not to the swift, but to those who keep on running. Have a plan for the day. As more requests come in for your time, decide whether it’s more important than what you’re doing. If it is, change course. If not, hold your course.

Either way, something isn’t going to get done today. Or this week. We have a finite capacity for work. We need downtime—time to rest, relax, and play—to keep going. You can push yourself to meet a deadline, but that needs to be the exception, not the rule. Push yourself too hard and you won’t get the results you’re chasing, just an expensive chicken dinner.

Question: How can you protect your long-term capacity to achieve results? Share your thoughts in the comments, on Twitter, LinkedIn, or Facebook.