What is a persuasive phrase for stopping smokers? Thanks :)

Try: "Smoking isn't permitted here", or: "Get that filth out of my home/my car/my face." About as good as any. 

Here's the thing, Lilly:

By this time, it's safe to say everyone old enough to light a cig is well aware of how ridiculously unhealthy smoking is. It even says so ON THE PACKAGE. Smoking makes slaves of its practitioners, and often kills them. Thousands die from smoking-related illnesses every year; this is all common knowledge and has been for decades. New laws even drive smokers out into the weather to sate their addiction. How can we expect any mere phrase to change the habits of someone who ignores all of that? Truth is, we can't. 

Here buddy I bought you a vaper pen!

There isn't one. Nicotine dependency runs much deeper than reason.

If you are talking about someone who has been smoking for years, there isn't one. It is an addiction and they are not going to quit until they are ready to do so. I know someone who was told his heart was badly damaged from the heart attacks (yes, more than one) that were caused by smoking and unfortunate genetics. He was told he needed a heart transplant or he most likely wouldn't live another few years. He would need to quit smoking before he could get the heart. He had a small daughter, and he chose the cigarettes over his daughter. Thankfully he has outlived their expectations, but now he is facing cancer as well. He finally quit smoking this year.

If actual negative aspects of smoking, like cancer, countless health issues, foul odour, social disgust doesn't 'persuade' people to stop smoking or better yet, don't start .. No catch phrase is gonna do the trick.  I suppose someone could come up with one to discourage it .. Awareness seems to be helping to a large extent.

This is what comes to mind .. "Don't smoke .. It's stupid?"

"I guess that you want to die fighting for your last breath in a slow, painful death."

I just tell them not to do it around me.  If they want to ruin their lives, you can't force them to stop.  Until they're ready to quit .. They're not going to listen anyway.