What do older men usually mean when they say, "When I was your age..."? Is this jelousy or am I reading way too much into this?

I just turned 34 a couple of weeks ago, and I've been thinking about something that happened recently.

For context, here's a recent picture of me: https://imgur.com/a/c5Err6b

I'm not posting it to fish for compliments—just to give some context for the story. I think I'm in pretty good shape for my age, but it's something I've spent the last decade working toward.

I've been lifting consistently for about 10 years. I don't mean on-and-off—I mean I haven't missed scheduled workouts, I genuinely enjoy training, and I've put a lot of effort into staying in shape. Fitness is a hobby I love, not something I force myself to do.

The other day I was at my parents' condo by the pool talking to one of the older guys who lives there. He's probably in his late 60s and honestly looks good for his age. We were chatting, and he asked how old I was. I asked him to guess, then told him I had just turned 34.

His response was, "Man, when I was 34, I had a flat stomach too."

I didn't take it as an insult, and I don't think he meant anything negative by it. But it got me thinking.

When people say things like, "When I was your age..." or "Just wait until you're older," are they unintentionally dismissing the work someone puts into staying in shape? Obviously, being younger has advantages, and I'm not denying that. But I also know I wouldn't look the way I do if I didn't spend years training consistently and paying attention to my diet.

So I'm curious from the perspective of other men over 30, especially those who are older.

Again, I don't think this guy was trying to be rude. The comment just made me curious about what people generally mean when they say things like that. Does it stem from jealousy? Dismissing the hard work you put in? Just being nostalgic?

Curious to hear some others' thoughts on this.

Thanks!