How you move defines how you live
Lifespan is pretty easy to define. It’s the number of years you live. Healthspan is intuitively obvious, but a bit harder to define. For simplicity, let’s agree that healthspan is a measure of how well, not necessarily long, you live. Further, let’s agree that one without the other—long lifespan with poor healthspan or short lifespan with rich healthspan—isn’t what most people want. This has the makings of a complex, nonlinear, multivariate optimization problem.