Absurdly Driven looks at the world of business with a skeptical eye and a firmly rooted tongue in cheek. 

I'm not sure why some people enjoy pain.

Many of these people are called entrepreneurs.

They seem to believe that pain is a necessary concomitant of success. 

Otherwise, the joy isn't as much fun, right?

What also isn't as much fun is when people push themselves too far. It's almost as if they're challenging their own minds and bodies to see how much they can take.

Worse, when it comes to endurance sports, it seems that the wealthy take a particular pleasure

Well, too many rich people never know when to stop, do they?

Some new research, however, attempted to find whether there really is a definable point beyond which it's deeply unwise to go.

Physically, that is.

Performed by researchers at Duke University, the study examined marathon runners and the way they expend their energy.

These runners all competed in the 2015 Race Across The USA. (Please, people. Driving across the USA is far more fun.)

The researchers found that energy expenditure plateaued after 20 days.

The conclusion was therefore blindingly direct. It is beyond the capacity of humans to burn calories at more than 2.5 times their metabolic rate.

If you push beyond that, your body will start to attack itself, breaking down its own tissue to make up for the fact that it doesn't have enough calories to keep going.

Study co-author Herman Ponzer put it this way: 

There's just a limit to how many calories our guts can effectively absorb per day.

Perhaps you, determined entrepreneur that you are, feel the need to push yourself physically as well as mentally.

Perhaps you get on your bike and insist on doing 50 miles every day.

Perhaps you run, run, run until you can run no more. Or until you have that important meeting with potential investors.

One can't help thinking, though, that if there's a limit for physical endurance, there's one for mental endurance too.

Moreover, the physical and the mental rather work in a tantalizing tandem, don't they?

Yes, you're going to test those limits, because that's how you are. Or that's how you tell yourself to be.

It's worth remembering, though, that there is a limit. 

It may not be so amusing if you go beyond it.

So take the day off. Go for a long walk. And imagine what life might be like if you didn't push yourself every single day.