EVERYDAY HEALTH - Immediate and Long-Term Effects of Quitting Smoking - Smoking Cessation Center, Nov 22, 2011

"As anyone who has tried to do so can attest, quitting smoking is tough. In fact, most smokers require multiple attempts before they are finally able to quit for good. With the commitment it takes to kick the habit — not to mention the damage those cigarettes have already done — it may be easy to say, “Why should I stop smoking now?”
But even if it’s tough, the benefits of quitting smoking start right away: Medical experts have found that a person's health improves within minutes of the last puff from the last cigarette, and continues in the years that follow."