年少不嗨老年痴呆
[nián shăo bù hāi lăo nián chī dāi]
If young and not crazy enough, old age brings regret, playing on the idea of enjoying life in youth to avoid regrets in old age. This has become a playful and somewhat exaggerated way of saying live life to the fullest now, as some elderly often look back and say they wish they had done things differently.