Went cold turkey on caffeine a couple weeks ago after sustaining a 3-6 cup daily intake for months. Been feeling unmotivated, taking the occasional mid-day nap, and having unpleasant thoughts along the lines of 'where's my god damn coffee' when urges went unfulfilled. The first 3 days were lazy, headache-clouded, and unproductive.

After that, though, I started to notice that I felt like working on projects in the afternoon and evening. It's a minor change in mood that's led to a major change in behavior, at least in the short term. Worth the costs, even if only for a brief change of pace.