How to do it with your brain:
A specific mental movement that can be trained as a habit that I learned in the context of limiting in-flight work: Label non-sanctioned work "bullshit". Internally declare it emphatically and emotively: "That's bullshit!!" This simple, charged internal speech is accessible to both system 2 and system 1 and can flow between them in either direction.
This is an extremely local notion of "bullshit"! It is a judgement of the triple: (you, <work item>, this moment). It is not an overall judgement of the work / cause / etc.. When slicing causes, it is the dedication of others to these obviously important causes that allows them to be bullshit to you in this this moment (emote: gratitude!). When slicing your own time, what is bullshit to you in this moment while you finish composing this email or whatever may become your top priority 30 seconds later after the current task is completed.
That presentation link has gone 404. Do you know where else it might be found, or remember the name or context of the presentation?
Full version with labels. Also,
Life Ascending claims that the neurons out in front may act as a "'waveguide'" to funnel photons more efficiently to the light-sensitive bits.
This topic is treated in much more depth in Live Cells as Optical Fibers in the Vertebrate Retina, which I read as marveling at how the darn thing works at all.