Two espresso shots every morning for the past decade. Most people don't think of caffeine as a drug, but it absolutely is. Tolerance develops rapidly, and missing my morning dose results in headaches, irritability, and inability to focus by noon.
At my tolerant dose, the effects are subtle — transition from groggy to functional, slight mood improvement, increased alertness. Nothing dramatic. Without it, I'm operating at a deficit. This is the hallmark of physical dependence.
I tried quitting cold turkey once. Two weeks of headaches, fatigue, and genuinely impaired cognitive function. Tapering is much more manageable.
Caffeine is so normalized we forget it's a psychoactive stimulant with real dependence potential. It's safe at moderate doses but if you find yourself unable to function without it, that's worth reflecting on. I've reduced to one cup from four and feel better for it.