I can't exist without my coffee. Don't even like the taste, just "do it" for the caffeine. I think about just injecting it into my veins. 
I genuinely love coffee (always black, no milk, no syrup, maybe, rarely, a pinch of nutmeg), and used to be properly worry-the-doctor addicted;
I worked in a paper mill, had my own office in the labs, with a drip-filter machine on the corner of my desk.
I'd arrive at work, make and drink a two litre jug-full (if you left it on the hotplate, it went foul).
Same again at lunch time and mid-afternoon.
At home, I had a traditional stove-top espresso machine which made six cups of espresso in one go. Six shots of espresso fit in one mug, which I would drink, go to bed, and sleep soundly.
I drank fresh-roast, fresh-ground coffee, so it was an expensive habit; when I was made redundant, I couldn't maintain the habit, so I went cold-turkey. A two-week, genuinely-blinding headache that no painkiller could touch, two months of sleepless nights, but I ended up clean and fine, and didn't touch caffeine again for a year.
That was twenty years ago: now I drink one or two cups a day, never after lunch.