I'm having an email / computer day too... Don't forget to stand up and move your body every 45 minutes. Research suggests that the extra circulation supports brain function and memory too (I mean it's obvious, but easy to forget - #irony ).
If you're in an office all day, be sure to move about, even if it's a quick stretch in a meeting room. Just make sure you don't stretch too far in a pencil skirt or suit pants. When you leave the room, always check for fabric tears. I speak from embarrassing experience 😳