It’s strange how much we change without realising it, and how the absence of such change in another can suddenly bring home the difference.

I have a friend, Ricky, who I have known for decades. He was the source of the rock ‘n’ roll CDs that defined our youth. It was from him I learned to headbang. We spent hours listening to Sweet Child O’ Mine and Patience by Guns N’ Roses. “Now that’s a love ballad,” we used to say. We lived for music. He continues to. I’ve changed.

Let me illustrate. Last week, I heard he had gone to Berlin, and assumed it was on a work trip. It turned out he had travelled there to watch Metallica play what may be their last live concert.

When I heard this, it was like a juke box was switched on in my head. I heard the thumping riffs of Enter Sandman and the haunting opening chords of Nothing Else Matters. But the nostalgia was followed by a cold question: Would I have done the same?

Even as I wondered about that, a bizarre coincidence occurred. Guns N’ Roses announced November tour dates in India. This is the group we had grown up worshipping. I had to tell Ricky.

He didn’t care. If anything, he was derisive. “They’ve gone to the dogs, man,” he said. He went on to talk of how lead singer Axl Rose “doesn’t sing any more, he croaks.” As opposed to that, he talked of how Metallica is still going strong. “They’ve aged formidably. They chose not to go down that slide of unmanaged decay.”

I can’t explain the grief I felt as he spoke. It was like something had withered and died, in seconds, right before me.

When our heroes — whether they be rock stars, friends or mentors — begin to age or change, we cannot help but feel a deep sense of loss. As long as they feel young, intact and invincible, they act as a buffer between us and the passage of time. They hold up the sky.

When they begin to slow down, hit a flat note, become bitter, or fade, that buffer vanishes. The myth shatters.

If the heroes of our youth are dwindling, it can only mean that we’re next.

Some people and some bands — Guns N’ Roses is among them — build their brand on raw, chaotic, unsustainable energy. It has to run out.

Is there another way?

Metallica offers hope, via reinvention. They don’t live like they’re still in their 20s. They treated aging somewhat like elite athletes do. reportedly following strict health regimens as they grew older. They travel with physical therapists and trainers. They shifted from raw, unguided energy to structured, deliberate mastery and, in doing so, preserved the myth.

In Berlin, as Ricky put it, one didn’t pity Metallica. One felt awe at their sustained power.

It struck me then that those of us who laugh at our own or others’ efforts to contend with aging — suddenly eating healthier, exercising differently, worrying about creaks and aches — ought perhaps to take it more seriously.

We are all fading. Why not prepare for it? Why not make room for it in others too; stop taking their strength and energy for granted, and stop demanding they be the towering monuments they used to be?

Every kind of relationship — all love — must evolve. I lead the way for my superstar uncles, while chatting about the superstars they’ve been. It helps temper the grief of watching them change.

Aging is mandatory. How we decay contains elements of choice.

(Charles Assisi is co-founder of Founding Fuel. He can be reached on [email protected]. The views expressed are personal)