Speaking of reducing activation costs, breaking big tasks down into atomic physical doable actions and figuring out the 'next action', GTD-style, can greatly reduce activation cost.

Technically, GTD only moves the activation cost around, though it does reduce switching costs by batching up the processing.

In other words, the "activation cost" of a vague/unspecified task is that you must first make it clear and specific. GTD doesn't eliminate this cost, just batches it up and advises you get in the habit of paying it early rather than late.