It fell out of my mouth before I could stop it.

Crap,” I thought, embarrassed. “I sound like my father.

The young woman grinned at me and I thanked her. Watched her walk away. She had just complimented me on how hard I worked out, the shape I was in.

She’s maybe half my age. Perhaps less. I’m 65. And yes, I’ve been a gym pig for 45 years.

Frankly, so what?

I had been watching her do something very different on a leg machine at the gym, and had been curious enough to ask. I’d never seen anyone use the machine quite that way.

This woman was happy to explain everything about the machine (most of which I already knew, which is why I made such an inane comment, above) and then I pressed her again on the more creative way she was using the machine.

She taught me something new and I was grateful.

Here’s what annoyed me about my knee-jerk comment, which also made me sound like a jerk.

We’ve all met people who love to brag about how long they’ve been at a particular job. At companies like BNSF Railways, you’re a rookie until you’ve been there at least twenty. It’s part of the culture. Time on the job implies power and seniority. At least on the surface it does.

But time put in neither guarantees competence nor excellence, and that’s my point. Lots of folks like to brag about their years as a way of being right. You could be doing a task for 50 years completely wrong or really badly (Congress anyone?). Or be so utterly stuck in your way of doing things that you are woefully behind the times.

I often see guys at my gym who’ve been there for decades. Their bodies haven’t improved. In one case one regular has gotten far more sloppy and out of shape. Clearly whatever he’s doing isn’t working. Excellence is about constantly challenging what we know, questioning whether we’re stuck in a rut, and constantly searching for better methods. Asking others for ideas.

Otherwise you just parade your years (as we say in the military, Time in Grade/Time in Service) as though that makes you an expert.

In the gym, if you spend decades doing precisely the same workout every week, the body gets bored, and adapts. You never progress. The body is lazy that way.

Like any other muscle-our ingenuity, our creativity, our closely-held opinions-those muscles alao have to be shocked and shaken up. Otherwise we stagnate and plateau. This was at the heart of the cross-training movement and it’s based in solid science.

When we’ve stagnated, the easiest thing is to lean on our laurels, no matter how flimsy they are.

Expertise and mastery come from being willing to learn from anyone. Anyone can offer us a new way of seeing, but we have to open, soft and curious enough to embrace those new viewpoints. That’s the essence of growth. Evolving. Developing a broader range of knowledge, skills, ideas and reference points. Testing what we know, and then discarding what is old, worn out and jaded.

As I watched this young woman walked away I thought about my weak-ass comment. First of all, nobody cares how long I’ve been doing anything. As an athlete, as a writer, doesn’t matter. What matters is the level of expertise I have, and how willing I am to not know. When I stop being willing to learn is when I stop adding value. At that point I’m nothing more than a braggart.

My long-time mentor Meg Hansson, whom I lost at 93, was studying and reading voraciously up until her death. She was fascinated with improving memory for those in her age bracket and also, how to improve water quality, which was her life’s work. She was never satisfied with what she already knew. There was always more. She trained her body three days a week, and was always researching other ways to improve her life through better nutrition or new studies. She pushed herself to learn. She taught me how to say “I don’t know, please teach me,” which is the antithesis of the arrogant and annoying ” I KNOW. I KNOW. I KNOW.”

Never ever, even on her worst day, would Hansson have stooped to claiming “I’ve been doing this for sixty years.” She knew such a statement was inane. When we stop learning, we start dying intellectually. The same thing with the body. When we stop moving, we start dying physically.

At that point, we really are just doing time. Whether we’re at the gym, on the job or learning to joust, we are no longer living. We’re justifying our mediocrity.