Why is quitting smoking hard for some, but easy to others?

I know its a force of habit. I did it for three and ahalf years.
I quit this year because I finally realized how gross it was.
Plus, what harm it actually was doing to me. I now just chew regular gum when I get a craving. It was easy for me to quit.
Your thoughts?Why is quitting smoking hard for some, but easy to others?
For some people addictions serve as an outlet for some other problem (mostly stress or anxiety). They have a dependence that is so deeply emotional as well as physical that it becomes a part of their routine and a part of how they cope with life. This is true for alcohol, video games, TV, food, and pretty much anything else. But some people get addicted for less "intense" reasons and never really form strong attachments to their substance of choice. The reason for quitting is also a huge factor. If a woman quits smoking because she becomes pregnant and doesn't want to hurt her child, she will probably be more successful than someone who quits because their friends or family want them to. Quitting, as you probably experienced, is easiest when you can be your own source of motivation.
Because everyone is different ;-)
well smoking which has ingrediants in them to make u want more..so wen u quite u have cravings...but some ppl are stronger against those craving than others
Strong will and dependacy......I quit smoking 3 or 4 times every day......