You can leave smoking, but you need to believe on it, if you keep thinking about smoking, then you wont be available to leave it.
I'm not a smoker, but it makes me disgusted to look others smoking that shit, I've tried 3 times in my life, first time when I was really young, about 7/9 years old. 2 others, were when I was already old enough. Like 18/20. You need to believe on it, and I know it wont be easy, but trust me, believe on it, and you will leaving it.