Yeah Kid, if your serious about this question, quit now!!!
I'm 24yrs old. Been trying and trying and trying to quit smoking. I just have ONE Weakness, and that's cigs. I was able to quit drinking, quit smokin weed, quit masturbating so much : ) .. but man, smokin is the worst.
Your so young, you could easily quit right now with no REAL addiction. My little brother did, he's 16yrs old. I saw him walking down the street with a cig in his mouth. I pulled over and hit him so hard, I had to put him in my car and drive him to the hospital. He never smoked again... I'm down to 10 a day, and it still kills me in the gym.. I'm an above average sized guy, but I could be FUCKIN huge if I didn't smoke. To answer your question, It kills you, your muscles, you stamina, and you self confidence... shit, now that I said that I don't know why I can't quit...
Fuck you cig manufacturer's
Peace..