It’s amazing how much good just going “if it looks/tastes like it’s mostly sugar and unidentifiable calories it almost definitely is very unhealthy for you” is. My wife’s a big soda drinker and my kids are starting to hit the age where many people pick up soda addictions. I push hard for them to mostly drink water and make sure to tell them how bad soft drinks are, and when they get upset about seeing the difference between what I say and what my wife does I tell them “you can make that decision for yourself when you’re a grown-up”