How to bring up the topic of smoking (vaping really) to a non user?

One of my good friends is back in town and has never done anything like that as far as I know, the subject has never come up. I'm sure some ents here have experienced this how did it go and how did you bring it up? He is not D. A. R. E brainwashed I don't think. Did you start with the union? I how did your friend react are you still friends?