I've been a 3+ pack a day smoker for 35+ years. Haven't had a smoke for 45 hours.
Both of my parents smoked like freight trains when I was a kid. I used to HATE riding in the car with them. I would roll the window down and look like a dog riding with my head hanging out the window! It gave me a strong desire to never take the habit up, and I didn't. I moved out when I was 20, and it took me several years before I quit being sick because of the 2nd hand smoke. I admire anyone who can quit smoking. It would have to be terribly hard!