Kostas quit a week ago, and he has some great advice - quit earlier rather than later.
I quit three days ago, having been a smoker three years - I am 23 now.
I had bronchitis and after that the constant throat clearing and the morning phlegm for more than 2 months without resolve, made me quit for good.
I was an athletic guy before the cigarettes took control over my life. I still remember the fresh air I would breath after a long run, as a non-smoker 3 years ago! I'm quitting now instead of being forced to do it in later years as the only choice to live.