My biggest gain productivity (and reduction in stress) came when I embraced the idea of writing everything down. (Thank you, David Allen!) The hard part is managing to always have something handy with which to do the writing.
My Field Journal Notebook works great when I'm at my desks, in a meeting, or even out to dinner, but it doesn't work as well for the odd bits of time during the day when things inevitably occur to me. It's too big to use when I'm standing on the bus during commute and it takes too much time to pack it up for transport when I'm just running to the restroom or stepping across the hall to ask a co-worker a question (and then unpack it when I get back).
How do I have a small, refillable, and secured writing surface (don't want to drop loose pages in the middle of the bus aisle) that includes a pen loop and a shoulder strap? DIY and paper type are highly negotiable; the notes have a half-life of about an hour, so this is definitely about function rather than form.
 Yes, a pen loop and a shoulder strap, 'cuz the American fashion industry has decreed that professional women are not allowed to wear anything so gauche as pockets. (Not that I care what the fashion industry thinks, but I can't buy what they don't sell.)