Spicy take:
The good is not a destination. It's a bearing you keep recalculating.
Evil doesn't need malice. It just needs someone who stops checking. The worst crimes in history weren't driven by monsters, they were driven by people who let the machinery think for them. The failure wasn't cruelty. It was mindless following.
Positive inversion: If the failure is not-seeing, then the discipline is looking. At the person in front of you. At the situation as it actually is, not as your comfort or ideology or habit needs it to be. This is harder than any act of will, because the self constantly warps the picture through your own biases.
Goodness isn't a set of principles you install and forget. It's a practice of noticing. And the moment you think you've got it figured out, you've already started drifting. Every fixed moral system eventually becomes the tools of oppressor the bureaucrats hide behind.
Evil is what happens when you stop adjusting.
Good is the effort of never stopping.