Well, I can appreciate your concern for your friends. But the bottom line is you can't quit for them. They will need to be responsible for quitting on their own. As someone that smoked for about 30 years, I can tell you that it is extremely likely, that every time you decide to remind them that smoking is bad for them and that they should quit, that they will resent your comment and eventually you. From my point of view, everytime someone would mention that smoking was bad for me, I wanted to say "Really? When did that happen?" I mean come on, do you really think we (smokers) are that stupid that we don't know smoking is potentially dangerous? Your friends will quit on their own, when they are ready, end of story. I quit myself about 5 weeks ago, so far so good, I just woke up and decided that not only was that something I no longer really enjoyed, it was preventing me from doing things I could enjoy So, I stopped smoking, cold turkey. No big drama involved, in fact I didn't tell any one for about a week so that I could work through it on my own without people reminding me that I wanted a cigarette.
At no time, while I was thinking it over the morning I quit, did I ever give any consideration to other people in my head going that is bad for you, you should quit.
Okay, now to tell you how I did it. After I decided on my own to quit, I mentally made a list of the reasons to quit, what I would get out of it. Saving money, breathing better, etc. Then, for the first few days, I focused on how I was doing. Not necessarily not smoking, but the reasons I wanted to quit. I would take a deep breath and at least in my mind, think that each breath was a little bigger. I would smell around my house and try to imagine that with each passing moment that it smelled a little cleaner. Everytime I walked my dog, I would take note that the walk was less stressful on my body. Basically, I just took careful note of every tiny positive change as it happened. I would pay more attention to the way things smell and really tried to take in the aromas, shampoos, soaps, food, etc. I didn't focus on the fact that I quit smoking, I focused on what was getting better. As weeks go by, I notice less dust in my house, my car stays cleaner, etc. I still think of a cigarette from time to time, but I try to take my brain right back to what I'm trying to accomplish, take a deep breath and try to remember why I am able to do that. So far, it's worked.