Andwan,
I am not sure how to turn "I will quit smoking" into something that doesn't focus on smoking. So I am thinking that your intention, "I am quitting smoking" will be just fine as an intention. But you still have to do the legwork - taking action.
Please read Erin's blog post here about that:
Law of Attraction and the Role of Action
Some people can quit cold turkey. Some need the nicotine patch. Some people take some sort of shot that is kind of like aversion therapy. Read up on what you can about others who have quit and find a method that is suited to
who you are.
Believe in yourself and live as if you have quit smoking. You must truly believe that quitting smoking is something you can accomplish, that it will happen. That is step 1. Step 2 is taking action.
I am unfamiliar with how to quit smoking so I have nothing to give in this department.
But believe in yourself. And be kind and forgiving of yourself if you do fumble when you quit smoking. Two steps forward, one step back. If it were not for the one step back, we would never learn and grow.
I know you can do it. If it takes a while, so what? Anything worth undertaking doesn't happen over night.