I stopped drinking coffee two years ago when I was suffering from some arrhythmia, and it solved my problem. I was drinking only one cup a day at breakfast, but I guess that was one cup too much.
I had severe headaches for the first three days, and felt sleepy in the afternoons. I would have never thought about it as a drug, but in the end, that's what it was.
Don't get me wrong, I really loved coffee. I would go to great length to get the freshest beans from specialized shops, that I would grind myself just before making coffee. It was quite a ritual!
As for vice, I do enjoy a little piece of dark chocolate (80 to 85% cocoa) with a cup of herb tea after lunch and dinner.
Indulge in your little vice, as long as it is done in moderation, it adds some spice to life!
Cheers!
Francois