I smoked for ten years. Took Chantix for a week about fifteen years ago, which increased the frequency and intensity of my suicidal ideations. I then quit for good, with help from the Carr book, about a year thereafter.
Quitting was horrible, but it got better. Now, the thought of smoking a cigarette is repulsive. Zero cravings, and the smell is highly offensive now.
I'm very thankful for Varenecline (aka Chantix/Champix); it's what got me to quit after many years of pack-a-day. I didn't even set a quit date when I started. That drug took away every tiny ounce of satisfaction I ever got from smoking. Every cigarette became a cigarette that did not give me what a cigarette is expected to provide. The best way I can describe what happened to me is that I felt like a non-smoker trying to smoke, and all I got was the scent and flavour of licking an ashtray with none of the brain-altering effects.
It's been over a year now, and I can't imagine going back. The only trigger I have is seeing someone else smoke, and even then it has never been more than a fleeting thought that dissipates within seconds. I know exactly what 2-3 puffs would do to me, and I have no interest in going back. I've never had the urge to buy a pack myself or to bum off someone. Smoking is now well into my past, and for that I am thankful.
I got the well-known "nightmares" from Verenecline, but I actually really enjoyed them. Those dreams were some of the most vivid and intense I've ever had the joy to experience. In fact, I still have the last 50 1mg pills leftover that I didn't need to use, and I've only kept them because I know I'll eventually use them just to revisit that kind of dream state. :)
For those in Europe, a similar medication is sold under the Tabex brand name. The active ingredient seems to be different (cytisine) but the effect is the same: no satisfaction from cigarettes, just the bad smell/taste plus some mild stimulation (at least I felt less sleepy in the first few days quitting with Tabex as opposed to cold turkey). I liked to visualize the effect of this drug as: binding to the same receptors in my brain as nicotine, robbing the dangerous molecule of it's power.
It still takes a tremendous amount of willpower to stay off the various forms of nicotine after the initial quitting. The pretense of having that first nicotine hit, seeking a consolation from life events, an excuse to make yourself feel better and all the other lies you'd be telling yourself are still very tempting (and exactly the reason I have been using the same pack of medication to __quit__ several times already.
Telling yourself there is no light switch in you, that you are stronger or better equipped than others, is a dangerous way to eventual relapse. Though for your own sake I really hope I am wrong.
Good sir, I regret to inform you that your assessment of my situation contains incorrect assertions based upon false premises, as I've made no such statement about my relative strength or equipment. I further regret to inform you that I've since been in the presence of smokers and cigarettes, through which no cravings arose.
Sir, I further regret to inform you that I've accidentally inhaled tobacco in recent years when being passed a (REDACTED BASED ON FEDERAL CANNABIS LAWS) that, unknown to me, had tobacco mixed in. I coughed, was disgusted, and had zero cravings for tobacco thereafter.
As such, there is no risk of relapse.
I do believe that my short stint consuming Chantix may have permanently rewired my brain's reaction to cigarettes.
Quitting was horrible, but it got better. Now, the thought of smoking a cigarette is repulsive. Zero cravings, and the smell is highly offensive now.
There's no light switch.
YMMV.