I spent years, years, studying and working in a health community that believed the planet would be healed if we just converted everyone to our way. But nowadays I just try to be as healthy as possible and sooner or later people might say "You look good, how do you do it?" or "How come you didn't put Aspartame in your coffee?"
The best advice is a good example. But the funny thing is I'm generally too busy noticing other people who know MORE than I do, and trying to figure out how they did it and how I can improve my life by listening to them.
You sound like a concerned caring friend! They are lucky to have you whether you ever say a word or not. Bon appetit!