I wake up a non-smoker, go to bed a full-on nicotine addict. How can I possibly quit?

I'm only seventeen. I've been smoking for three or so years, addicted for almost one. It seemed to get easier when I got my license and a car, because I could smoke whenever I wanted. Now that I'm getting to about a pack of cigerettes every three days, I really want to quit. Not to mention the fact that my chest constantly locks up and my lungs ache from the back. It hurts really bad to breathe sometimes, depending on how much I've smoked that day. It's affected my running and I hate smelling like cigarettes when I walk into work. I feel guilty that the kids have to smell it on me, although I do use hand sanitizer and perfume as much as I can. If my parents knew, they'd be so disappointed.

But back to the point here, smoking has done nothing for me but take away my money and my health. Beginning was dumb, and I was not smart when I thought I'd never get addicted. So my question is, without getting another adult involved, this means no counceling or medication, how can I possibly find the courage to quit? I've tried many times before, but I always get the worst cravings and end up buying a pack. Help?