Millions of people know from personal experience that smoking is a tough habit to kick. The reason is that nicotine is addictive. Even though nicotine’s high isn’t as dramatic as cocaine or heroin’s, it’s equally as addictive as those illegal drugs.

And nicotine withdrawal is very real. It’s why so many smokers try many times before they finally quit for good.

Nicotine affects all areas of your body, from your heart and blood vessels to your hormones, metabolism, and brain. When you don’t have it anymore, you go through withdrawal. You’ll physically crave that nicotine hit and become irritable if you can’t have it.

Nicotine withdrawal usually lasts only a month or so, but you could be fighting the mental battle against cigarettes for a long time.