Ditching caffeine did wonders for me. While I tend to feel a little less "manic" when I'm focused on something, I'm also way more clear headed so I'm certain I'

Ditching caffeine did wonders for me. While I tend to feel a little less "manic" when I'm focused on something, I'm also way more clear headed so I'm certain I'm actually more effective and thus able to reach a much deeper level of concentration. And don't even get me started on how much better I feel first thing in the morning, or how I can get through a whole week now without headaches, or how my energy levels don't spike and crash like crazy through the day, or how much better my digestive system feels without all that coffee in it... and what all those things do to one's concentration. It's insidious as well, because you gradually drink more over time; nobody goes from a standing start to 5-8 mugs a day. If they did, they'd feel like hell. So as you seem to acknowledge, after over a decade you're not even making an informed choice any more; there's not been a single moment in all that time that you haven't either been affected by caffeine or it's temporary withdrawal.