It's Charlie's soul," he repeated. "Or more accurately, it's a holographic representation of the dynamic electrical system that embodies the consciou… - John Scalzi

“I didn’t say that,” Szilard said, in a tone that implied that perhaps he had.

The problem with aging is not that it’s one damn thing after another—it’s every damn thing, all at once, all the time.
You can’t stop aging. Gene therapies and replacement organs and plastic surgery give it a good fight. But it catches up with you anyway. Get a new lung, and your heart blows a valve. Get a new heart, and your liver swells up to the size of an inflatable kiddie pool. Change out your liver, a stroke gives you a whack. That’s aging’s trump card; they still can’t replace brains.

In this universe, experience counts.