You must have noticed: I learn a lot of GTD from doing things with my kids. I find children a good model: the main difference between kids and adults being that grown-ups are way better at inventing some specious reason for the daft things they are doing...
My latest little anecdote was another floor-cleaning clinch. My eldest son, Matthijs, was looking at his highly untidy floor in resignation, so I made him a bet that he could have it entirely clear inside two minutes. That sparked his competitive nature and he was done inside one minute and forty seconds.
But this is not about motivation: the reason I made the bet and the reason he got done so fast was that there was nothing on the floor but knights and lego. All Matthijs' knights go in one drawer and all his lego goes in another. He did not need to spend any time deciding what to do with the thing he had in his hands.
For us adults: be very aware of the effect of sharply defined storage and filing. If you can take the e-mail, report, technical specification you currently are looking at and file it instantly in a place where you are sure to find it you will have no difficulty letting go of it. If it is neither knights nor lego you may have difficulty getting it off your "floor".