According to the ancient yogis, age is measured not by years, but by the flexibility of the spine, which naturally degenerates over time (this is good news for me since I just became a year older, and my spine seems to be in relatively good shape). However, there is a pose called wheel—a rather intense backbend—that I still find quite challenging if not darn near impossible (there's a lovely supported version that I can do handily, however). In this pose you basically plant your hands and feet on the ground and lift up into the shape of a wheel (you begin on your back face up toward the ceiling; check with your neighborhood certified yoga instructor for details!). Not easy! I’ve heard tell that the venerable BKS Iyengar as a young man (master, appropriately, of the very popular style of yoga called Iyengar yoga) used to practice this asana (or pose) on discarded tires.
Well, that's all fine and good, but I would like to add that in addition to the flexibility of the spine, the thing that really keeps folks young is a flexibility of heart and mind. As I see it, those who embrace life with an openness and grace of acceptance and flow, are those who seem to do better in terms of aging. A sixty-ish fellow I know, for instance, just keeps racking up physical problems and diseases. Divorced, he won’t date a certain kind of woman (only slim blondes need apply), will only eat a certain kind of very bland, American food, and heaven forbid would never even consider entering a yoga studio for fear that someone might be chanting. In the meantime the problems just keep multiplying, and the more ailments, the more meds. The man appears much older than his sixty years. While I feel compassion for this fellow, he’s also a frustrating bloke to spend any time with.
With all due respect to the ancient yogis, who certainly knew what they were talking about, I would like to submit that while a flexible spine is an advantage it’s the open heart that’s the ticket. But I will also concede that the yogis knew their stuff—it’s virtually impossible to do a backbend without simultaneously opening your heart.