The key to the method's success, I suspect, is the combination of ruthlessness and charity. You must go through every item, making judgement on each one, and you must be brutally honest about how each item makes you feel. No shirking, no softening the truth to play nice.
But at the same time, it's a constant affirmation of each discarded item as a gift, as a servant that served as best it could, the recurring "thank you for your service"--a steady wash of gratitude even for these things that are now unneeded or unwanted.
Hard work, but it brings with it much joy.
(The other major discipline this year is to absolutely give up internet access in the mornings and attempt to minimize using it at home in general--so far my productivity and general sense of wellbeing have both gone through the roof, so I think it's a practice that will need to persist even after Easter.)