I've been a 3+ pack a day smoker for 35+ years. Haven't had a smoke for 45 hours.
what worked for me was not being around people that smoke
I'd travel a bit when I was younger, and I'd go weeks without a smoke
then id come back, my sister smoked, my friends smoked, and within a day or two I'd smoke again as well
must done that a dozen times
finally moved away, got some not smoking friends and been smoke free ever since