Former caffeine addict here. No coffee, but I used to drink at least 4 cans of diet soda a day, or maybe half a liter. It was pretty much a non-stop infusion of caffeine from morning to late evening. But there was a problem: I had to urinate all the time. Once an hour wasn't unusual. And it wasn't just the frequency, it was the intensity: when I had to go, I really had to go. Holding it was not an option.
So when I decided, in January, to take the April MCAT, one of the first things I wondered was how on earth I was going to make it through each section without using the john. I wondered about Depends. At that point I realized something was seriously wrong with me. Caffeine was controlling my life, and I decided that enough was enough. I quit cold turkey on a Friday so that I could "recover" over the weekend. It was hell -- headaches, fatigue, irritability -- but after a few days I was free. I found that I could make it through a long day of work just fine without caffeine. And I was relieved that I could go for hours on end without needing to relieve myself. Potty breaks during the MCAT were a non-issue. The incessant urge to pee was gone.
I still drink a lot of diet soda, but it's mostly caffeine-free (I know, I should just drink water, and I do sometimes, but it's so boring). I still drink caffeinated beverages too, sometimes, but never more than one a day. I often go caffeine-free for a few weeks at a time. When I do have caffeine, it definitely picks me up, but I'm determined to never become physically dependent again.