You just have to fully understand how disgusting and dangerous it is. My friend, more like my brother, he used to smoke cigarettes for years. He tried to quit so many times, but then would start again later. Then one day he just got a new pack, and I ripped apart every cigarette in the pack on his back yard table so he could see what is in them. It isn't just tobacco, tobacco is just one ingredient. When they refine oil into all the things like gasoline, diesel, propane, plastic, and everything else they make it into, there is some garbage sludge left over that they can't use for anything. And they take this left over oil sludge and mix it together with tobacco, then turn it into a kind of paper and cut this paper into little strips, and that is what is in cigarettes. They do this just to make them even more dangerous and poisonous, and because it saves money if each one has some filler and doesn't need to be all tobacco. I was explaining this to him and showing it to him, and we were feeling it in our fingers. And touching the "tobacco" paper, it melted and got this dark brown slime stuck on our hands that really is like a petroleum byproduct. After this, he never smoked another cigarette ever again. After all those times trying to quit, and all he really needed was to see for himself how bad they are.
You can't just tell yourself that you don't want to do it anymore. You have to fully understand how disgusting and damaging it is and know all the details. Then you would be too disgusted to ever touch it.