>>Have gone 12 days without a cup of coffee.
>>
>>Torture!!!
>
>I smoked for 3 or 4 years and quit. It wasn't very hard.
>
>I eliminated all caffeine just to see if I could do it a few years back. A solid week of lethargy and headaches ensued. Way harder than nicotine.

That's actually a physical reaction. The body gets used to it and rebels when it doesn't get it.