Kari, my new personal trainer, had me down on the mat when, in the middle of a tough set of obliques, my T-shirt rode up and revealed "it".
It was a 0.4m-long scar that runs from below my navel to my breastbone.
Kari did not hesitate to ask: "What's up with your scar?"
Although "my scar" - and I do feel proprietary about it - has been a part of me for more than three decades, an answer still does not come easily.
My first inclination was to pretend I had not heard the question.
Then, I briefly considered telling her a flat-out lie: "I was shot in the stomach." (I once knew a guy with a similar etching on his belly that was caused by a gunshot wound.)
Finally, I settled on the truth.
"It's from a long-ago cancer surgery," I explained, outing myself as a member of the "cancer club".
In 1984, after an eight-hour operation to remove cancerous lymph nodes from my abdominal cavity and two weeks in the hospital, I went home with my scar.
It is a remarkable wound - sutured with silk, woven with wire and zipped up with no-rust staples.
At the time, I was single and 26 years old.
For more than 30 years, I have wrestled with how to come to terms with all that it embodies - and how to talk about it.
At first, when the wound was still red and raw - and so visible, before my chest and belly hair grew back - I did not want anyone to see it.
I was embarrassed to take off my shirt in a locker room or at the beach.
At home, alone, I would undress in a dark closet to make sure I did not catch a glimpse of it.
Every so often, I would step out of the shower and see that rough-hewed line and it would set off an avalanche of emotion.
It was not just the obvious disfigurement. The scar represented the loss of my younger self's sense of invulnerability and - no surprise - triggered a fear of death.
In an interview, Dr Jeffrey Marcus, chief of paediatric plastic surgery at Duke University, who has treated thousands of patients in his 15-year tenure, told me that we all have very personal responses to disfigurements such as scars.
"A scar is a physical deformity. It's a physical difference," he said, adding that scars ignite questions of identity because other people "tend to draw conclusions or make assumptions about attractiveness, intelligence, even capability, based on something they see".
I was sure others would use the scar to judge not just my appearance, but also my sexual prowess.
Being single presented a wrenching set of dilemmas. What was I supposed to do when going to bed with someone for the first time?
Let's face it. Nothing breaks the mood like announcing: "Hey, I have a big scar because I had cancer."
When I rebooted my dating practice, I made sure to keep the lights down low - if not off - and sported a tank top in bed.
I hoped to pass for shy rather than ashamed.
Most of my dates were decent types or maybe they were myopic or shy themselves.
One person who asked me about the scar did not take more than two breaths before saying goodbye: "I just buried my partner who died from cancer. I can't go down that path again."
The Americans With Disabilities Act may protect people like me from discrimination on the job, but we are on our own in the bedroom.
By my mid-30s, the scar had softened and faded.
In that decade, my shame had slouched into shyness and, now, I was toddling towards acceptance.
I took off my shirt at the beach. I got naked in the bedroom. I looked at myself in the mirror.
In my 40s, I got married, scars and all.
What had once been a stark reminder of my illness had become something else altogether.
Now, it was a testament to my survival.
Reading Cormac McCarthy's All The Pretty Horses one afternoon, I stopped in recognition when I came upon this line: "Scars have the strange power to remind us that our past is real."
My scar had become a talisman of sorts, a visual and lasting connection to my history.
As Dr Marcus told me: "Some differences can be positive too."
After 12 years of marriage, my spouse and I recently separated.
I expect I may be re-entering the dating scene before long.
But now, I am in a different place.
Sure, I still have some unease about "it" from time to time.
But three decades after my surgery, I keep coming back to this realisation. My scar is visible proof that I have survived.
Without it, I could not be whole.
It is, literally, what binds my torso together. Time may heal all wounds - if not all scars - and that is just fine with me.
• The writer is an American journalist and author who writes frequently on modern-day etiquette.