I don't drink coffee much. I only drink when I was think about somethings or when I on the exam period or when I stressful. Maybe in the future I'll drink coffee because at that time, I need to in full command of my faculties.
If I don't have my morning coffee I feel rather lethargic but worst of all a headache will start festering and progressively get painful. I found that out the hard way! So now I always make sure I have my morning coffee.