What has "design" to do with anything? Obviously, a healthy life leads to a healthy life. That is a trivial truism. I try my best to do that. But you come down with some debilitating problems that baffle your doctors and interfere with your own mental acuity and energy, and then see how that works out. I'm not saying that drugs are any cure, because they haven't been and probably won't be. But I am looking into supplements for brain, liver, and gut. Also, have fun with atrial fibrillation and flutter if they intrude on your life. Surgery is about the only way to eliminate them. Good luck on living a healthy life. It is not always under your control. I've attended funerals of too many friends who lived healthy lives (which is no argument against a healthy life---just that it does not make you invulnerable).