One day, you wake up to realize that a particularly vital assumption about the world is wrong. Everyone who buys into it is wrong. Which is almost everyone in the world. Everything in the world that depends on it is wrong. Which is almost everything in the world. Now what?
Waking up is an apt way to put it; the reconfiguration of realization is not unlike passing through a slow instance of the stage of booting up in the morning. (Who am I? What am I doing today? How did I get here? What are my axioms? Oh, right, got it). The "oh, right" part might take longer, however, as pulling out one of the pillars of your constructed world generally means radical change. We humans are hardwired to hate change almost as much as we hate failing to share the same worldview as our peers.
But there's no going back from realization. Either you proceed according to your new understanding of the world, and figure out just what that implies, or you become good at living a large and uncomfortable lie. Embrace revelation or run from it.
So, one day, you wake up to realize that aging is the worse bane suffered by humanity, and the people of the world sleepwalk through an unending holocaust of suffering and death caused by the decay of their bodies. Furthermore, it quickly becomes apparent that large-scale work over a few decades will plausibly lead to medical technologies that prevent age-related frailty, disease and death. Acceptance of aging in this circumstance is like a slow-motion mass suicide, day after day after day.
But still it goes on, the grinding of the cogs, the great wrong that everyone just goes along with as though it were nothing.
Now what? You've seen behind the curtain. You have a secret that no-one you know takes seriously. Yet, you realize with clarity that nothing else you ever do in your life will be as important to the future - your future, humanity's future - as any time and effort you put towards bringing forward the defeat of aging. That's going to be hard to put back into the box, trust me.