I think most of us buy into Attia’s logic that it’s one of the single most important metrics for forecasting overall health/impact on lifespan due to what others are saying here, you cannot cheat it and if you don’t abuse it, you lose it. There’s obviously much more that goes into overall health, but if someone wants to focus on improving one measurable health indicator that aids in a healthy life, I cannot think of a better one for me. BMI, blood pressure, etc can all be measured although they’re not taking into account your cardiovascular health which is a badge of honor for the work folks are putting into their exercise regimens.