Most people are looking at the moment in front of them, and that's the moment that they're dealing with Shem and Cham. Think about this moment after it's already behind them. They imagine, “What will this look like after I've done it?”
Someone once asked me, “Rabbi, I have a big yetzer hara (evil inclination).” I'm not going to get into exactly what his yetzer hara was, but he said, “I have a big yetzer hara, and I can't stop myself.” And I said, “Listen, let me just ask you this: after you've done this aveira with this sin, whatever it is, how do you feel afterwards? Do you feel great?” He said, “No.” He says, “I feel ashamed. I'm embarrassed. I feel guilty.” I said, “Okay, and how do you feel when you're doing the aveira?” He says, “When I'm doing the aveira, okay, maybe it feels good.” I said, “Well, how long does that last for?” It takes a few minutes, right? However long—an hour, a day—it doesn't matter. However long that sin is.
Think about how much enjoyment there is versus now the guilt, the shame, the upset, the anger, and the lowered opinion of yourself. How long does that last? Weeks, months. Look at what you're trading.
So I said, “When you are stuck in a situation, just ask yourself, ‘Okay, I'm going to do this. Let's imagine—now I haven't done it yet—imagine I did it already. And then what? And then what? What will I have from it then?’” That's the achoranit of Shem and Yefet. That's the backwards. The pasuk (verse) says—I’m going to read you these beautiful words: “And they covered the nakedness of their father. And their faces were turned the other way.” Once they could imagine the deed behind them already, they were in a situation where they were not actually going to get into the sin in the first place.