I quit smoking cold turkey the day of my heart attack in 2014. I had a carton a week habit but fear is a wonderful motivator! I admit that I did start using an E Cig when I got out of the hospital but I had a plan. When I first started, I had them mix up the "juice" so it had the same nicotine as the cigs I was smoking.
Then every time I bought a new supply of juice, I had them lower the nicotine by one point. Eventually, I started forgetting to take my E Cig with me because it was no longer a habit.