Smoking - by Laura

Here's a dialog Laura had to make up between a smoker and a non-smoker:

A: I think I need a cigarette now.
B: What? You smoke?
A: Sure. You want one?
B: No, I don't smoke. It's not good for your health.
A: Yeah, right. Everyone smokes. It's normal ... and I'm fit.
B: I don't feel happy about it. Many people who smoke are very ill. It is not good for you.
A: It's my life. I can do what I want. You don't tell me what I do.
B: I would like to help you!
A: How now? Mind your own business. It's my life.
B: But I'm your good friend. I want to help you.
A: Don't bother me. When I think I need a cigarette, then I smoke.
B: Ok, then do that. But it's not good. Be that as it may. But not near me, go out.
A: Ok, I'll go out. But tell me nothing about your opinion. It's my life.
B. All right.

What do you think about this dialog? Is it realistic? Maybe someone has had a similar conversation? Please comment.