Yaya's is right. I ran a 1 km fitness test a week after quitting and had fluid in my lungs afterward. Those commercials about the truth are excellent. Tobacco manufacturers don't just roll tobacco up into cigarettes. The tobacco in cigarettes is processed the same way paper is made. It is pulped, chemicals removed, chemicals added, dried in thin sheets and shredded.
Smoking is a habit and an addiction. You have to treat it as both. And it's like alcoholism, an every day battle. I miss my smokes every day. Get all the help you can from your Doctor. Remember, as with any goal, people expect you to fail though they encourage you to succeed. They aren't being mean, they don't want you to be disappointed.
Smoking is a very hand-to-mouth habit, watch what you eat when you are quitting. Don't expect to have more money, food to taste better or things to smell better. Have a goal for your cigarette money, mine is riding lessons. I don't deliberatly set money aside I just know that at $5 to $7 a pack Cdn, 3 to 5 packs of smokes are equal to one $25 per/hour riding lesson once a week. ( My father, ever the voice of reason, pointed out that I gave up one dangerous habit that will kill me slowly for another dangerous habit that will kill me instantly, thanks Dad.)
I quit cold turkey. You may even have to alter your social circle i.e. your smoking buddies at work. It all depends on how bad you want it. My son was always sick when we smoked. I didn't realize what an impact both of us smoking had on his health.
And if you don't smoke don't start.