So here's the deal. I'm a 21 year old male. I have been a heavy smoker for about 3 years of my life. The longest I have really been able to stop smoking cigs was about 2 and a half months. Here's my experience to date now.
I started smoking for real in response to mounting stress in my life. I was spending my time with a woman who just stressed me the **** out, and she got to me. About two weeks or so of smoking, I started coughing green sputum. This scared me, but more stress just kept piling on in my life, and I continued to smoke. The friends I made in school all had a comical adherence to smoking ("man, smoking is good for you brah"), and I continued smoking socially.
Soon I was in the process of switching schools. During winter break, it became clear to me that a lot of my close high school friends had also taken up smoking. Predictably, this gave me further validation.
About a year ago from making this post, I started noticing that my mucus had streaks of blood (Note: to date, the only mucus with any blood has come out of my nose, not as a result of coughing). Naturally, this freaked me the hell out, and I just lost it. I resolved I would do away with tobacco, leading to the two and a half months noted above. This turned out to be my worst semester of college. At the time I was facing not only social dissonance with some of my peers, but also difficult classes.
Part of what I believe helped me stay quit for some period of time was that I avoided a lot of situations that could yield stress. But this went to devastating levels: me not adequately doing my school work, sleeping a shitload, drinking a ton, and generally killing time. I started smoking again because I just couldn't avoid these things anymore. It has been difficult since then.
Now recently, I got a cold where I started coughing the green sputum again. I managed to make it through most of the week without smoking, about 4 out of the five days that I was sick. Lately, my sputum is opaque and sticky as it has been for awhile.
Whats my point? Although I am most certainly addicted/dependent on cigarettes, I am under no delusion of their effects. I have mentioned my symptoms, but I am constantly being reassured that I'm not screwed at this current time and that if I quit, I can turn out ok. I ask my friends if I'm totally ******; they tell me, you're too young to be that afraid. One of my friends who studies pre-med (not that it matters) if you are able to quit before 25, you'll probably be fine.
So my question is, if I can just cut down and slowly waver off of cigarettes in the hypothetical timeframe mentioned above (hopefully much much sooner), will I be ok and will smoking cessation be a time where my lungs heal and I become healthier.
Quick recap of noticed symptoms: from green, sticky sputum, to generally clear sticky sputum, occasional blood-streaks on mucus coming from the nose, some chest tightness, cough.
It's true, you are very young--but the sooner you quit, the better, as you already know.
I know someone years ago who said he was going to quit by a certain age, and, well, did not. Just keep trying--eventually you will stop for good. Good luck and best wishes to you!!