Which quality does not differentiate the young-old from the old-old?

Happiness does not differentiate the young-old from the old-old, it will never depend, nor be conditioned by age, comes from different sources and forms, a person can be 60 years old and be happy for a reason totally different from an 80 years old, unlike health, work or money, which probably depends a little bit more on the physical condition granted by age.