Early in the short, Superman (as Clark Kent) discusses with Billy Batson over breakfast about how being good is harder than being bad. Later, when Captain Marvel is holding Black Adam by the throat, Superman echoes back to that discussion to get Captain to calm down.
Clark: (noticing the mark on Billy's right cheek) What's that on your face?
Billy: Eh, it's what you get for trying to be good. Should've just kept my mouth shut. "Be good and good will follow." That's what my parents used to always tell me. But you know, Mr. Kent, I was good before they were taken from me, I was good at the foster home, and I was good 15 minutes ago. I'm starting to think being good isn't good for me.
It seems that way sometimes, doesn't it? But that's because good is hard. Bad is always easy.
Superman: That's enough!
Captain Marvel: No! I have to, to protect them!
Superman: How? By being like him?
Captain Marvel: By being stronger than him.
Superman: Then be strong. Be good.