Addiction already is a form of lost self-control, even if it's thought of as a personal choice to smoke, so if you try to do too much to force the smoker's hand into quitting you might be seen as a controller. This can lead your loved one into closing off communication on the subject or can cause them to do things like sneak in more cigarettes out of your sight.
Some over-controlling acts might include making an appointment for a smoker before he or she has decided to try quitting. Not only will many health professionals refuse the appointment unless the smoker initiates it, but chances are the smoker also will be resistant, defensive or resentful. Let the person who's controlled by nicotine have control over when it's time to get professional help or to choose a program, and then the ongoing support of friends and family may be more welcome.
And forcing the issue of smoking with an ultimatum, for example telling a romantic partner you'll end the relationship if he or she doesn't quit smoking, not only has the potential to come off as a threat, but it also can become meaningless if it's a repeated threat that's never followed through.