When people plan for their own old age, they often focus on life expectancy. But perhaps there is a far better measure: one's expected *health span*. While life expectancy focuses on how long you'll live as a raw number, health span refers instead to how long you'll live in relatively good health, free of serious disease. Put another way, one's health span is the period of reasonably good quality of life before age or disease starts taking its toll. Unless you die prematurely, [[Everyone gets old unless they die prematurely|your health span will always be lower than your life expectancy]]. This is a key distinction if you're planning your future. If you're 50 now and your life expectancy is 82, but your health span is only 72, then you're fooling yourself to believe that you have more than three decades left to travel the world. Because you likely don't. In my own [[Life Block Planning]], I chart my life expectancy as 86 (though I consider my [[Death Date]] to be a few years earlier), but I'm planning for my health span to end a decade earlier. Because my plan explicitly takes this into account, I've prioritized some experiences earlier in my life than I otherwise might have. Indeed, my plan anticipates no major travel after my health span date. So I plan on visiting every place I want to before that time, and any travel I do manage to do after that date is an unexpected happy bonus. This date is simply a best guess, of course, based on some calculators that look at how people with similar age, family history, and lifestyles fare. In fact, there isn't an easy, well agreed upon methodology for calculating health span. And as we develop better treatments, this number should rise higher and higher. Even with this uncertainty, health span remains a useful number. Explicitly planning for one's expected health span helps [[Prioritize experiences over things|prioritize experiences]] you want you have, plan more effectively for the future, and is a hedge against failing to see [[You don't realize your age|one's own inevitable decline]].