You're only as young as the last time you changed your mind.

The line recasts “youth” as a mental and moral condition rather than a biological one. To be “young” here is to remain cognitively flexible—willing to revise beliefs in light of new evidence, experience, or insight. Conversely, the longer one goes without changing one’s mind, the more one risks ossifying into habit, ideology, or complacency. The aphorism also implies that growth is inseparable from self-correction: intellectual humility and curiosity keep a person psychologically vital. Read this way, the quote functions as a compact defense of openness and experimentation, suggesting that adaptability—not age—measures a person’s continuing capacity for renewal.