As someone who had to quit caffeine for health reasons (it gave me continuous withdrawal headaches, even through the normal course of a day), I urge everyone I know who drinks a moderate amount of caffeine and tolerates it well to keep at it
Even a year later (and the withdrawal symptoms gone), I still miss the mental sharpness and harmless 'attention boost' I could get from caffeine when I needed it. Once in a while, I'll let myself have a cup of caffeinated tea, and I really appreciate it to the fullest.
(Yesterday, I had to take care of a sick child after a terrible night, and I really really wish I could have taken a large coffee and be my full self, instead of a muddled zombie. I compromised by having some tea, and immediately felt better. But I know that I can't use that trick too often or the migraines will come back).