The boarding process for a recent flight required going up a modest set of stairs. Greatly slowing it all was a woman carrying at least 80 more pounds than were optimal. Every step was a labored exertion.

She looked to be in her 40s and in the bloom of health other than the excess weight. I thought: “This can’t be fun. Why doesn’t she take better care of herself?”

Later in mid-air, I’m reading about a life-threatening condition that has been sending fitness fanatics to the hospital. Rhabdomyolysis causes horrible pain, turns the urine brown and threatens the kidneys. Cases are rare but seen in exercisers engaged in killer workouts, notably brutal Spinning sessions (stationary bicycle drills). The stricken tend to be new to the exercise, and their bodies haven’t adjusted to the physical demands.

Even on the matter of fitness, our population has become polarized. Large numbers have surrendered to obesity, while others seem willing to suffer hugely in pursuit of uber-fitness. So many of us, it seems, cannot enjoy good health in a relaxed way.

This could be linked to diverging social and economic trends. There are people who’ve basically given up on themselves in multiple ways. And there are perfectionists driven to excel in every endeavor. They’re not necessarily on the path to wisdom, either.

“Extreme exercise” may be propelling some marathoners toward an early death, according to a piece three years ago in The New Yorker. Cardiologists argued that it damages the heart and can be blamed for sudden deaths among some heralded athletes.

Dr. John Mandrola, a heart doctor at Baptist Medical Associates in Louisville, Kentucky, himself a former elite cyclist, saw the problem as psychological as well as medical. It involved a constellation of questionable lifestyle choices. “The inflammation of excess,” he called it.

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“It’s not just being on that edge in a race,” Mandrola said. “It’s being there in training, at home, at work, and for decades. Always on the gas — yes, this is the problem.”

I live surrounded by both wings of the fitness spectrum. But there is also a centrist group to which I seek membership. The third way combines a moderate exercise regimen with a way of life that incorporates exercise in everyday activities. The members garden. They walk, and they vacuum. They peel carrots as they cook generally healthy meals.

My gym has a device called “the sled.” The sled is basically a heavy platform. The muscle guys pile it up with weights and then push the big thing across a resistant floor covering of fake grass. Whenever my real grass needs mowing, the sled comes to mind.

On muggy days I’d rather do my taxes all over again than mow — and my lawn is not especially big. But then I think, “Sled.” I drop the charged battery (it weighs) into the mower and push, push, push.

At the end, I award myself several imaginary gold stars. One is environmental — for using a rechargeable battery and mulching (no, I’m not giving up my lawn). Another is economic, for not having paid someone else to do it. And the third is physical. I did the sled without the glamour of the gym, such as there is.

The medical literature on extreme workouts emphasizes that running, cycling and the rest are excellent as long as you train to do the harder stuff and know when to stop.

“Darwin was wrong about one thing,” James O’Keefe, cardiologist at the Mid America Heart Institute in Kansas City, Missouri, told The New Yorker. “It’s not survival of the fittest but survival of the moderately fit.”

Ommmmmm.

Froma Harrop is a syndicated columnist with Creators.com.