Yeah, caffeine... I find that I can stop anytime I want. For weeks at a time!
(Off-Topic rant regarding carbs: I observe that our brains require sugar to function, neurons can't metabolise anything else. Well, there is an emergency fallback to starvation mode, where a sugar-like molecule is derived from proteins, which our neurons can also use, but that requires the body to be in literal emergency starvation survival mode, which has its own set of health implications in the long run, as far as I know. So while carbs have a bad reputation currently, carbohydrates are literally what our minds and bodies thrive on. Of course, this does
not mean refined white sugar, white flour, and so on, but complex carbohydrates complete with all the fibres, and fruit (whole, not juiced). So if someone means "pasta" or "white sugar" or "high-fructose corn syrup" when they say "carbs", then I'm totally aboard, but I feel the current fad of generalized poo-pooing of "carbs" is harmful).