Why cant i quite smoking?

you have to figure out if the addiction is physiological, psychological, or both and then decide how to go from there

Because you are lack of motivation.
You can. I just quit a little time ago and it was hard and still is. So if you know that before you stop, thats a good thing. Because then you kind of expect it. Anyways, find out what kind of smoker you are and then find the best plan for you: get rid of one cigarette a day or stop from one day to the other. Or do it in a group. Or buy yourself something for every week of non-smoking. Just think about yourself and the situations you smoke: avoid those in the first three weeks. And last, but not least: the addictive stuff is out of your body in 6 days. 6 days. That is not long at all. After that its just mental. So it really is in all in your mind after 6 days. You have to find out, if your mind is strong enough. Good luck!
Nicotine is highly addictive. You have an addiction to it. It is had to break any addictive drug especially cold turkey. Try to cut back your cigarettes until you only smoke one a day, then go 2 weeks without it. After two weeks the with-drawls are gone though you may still have a craving. It's kind of like caffeine. If that doesn't work it may be a habitual addiction, try to suck on Dum Dum suckers when you want a cigarette, it worked for a friend of mine. Hope that helps.
Two weeks with-drawls gone- family physician
It's easier said than done.

Nicotine is extremely addictive.

I've tried to quit smoking at least 20 times in the past 10 years. I've given up. I'll quit eventually when I'm really ready.
because you are habtual may be,you can quit by using chewinggems