Now, all this space talk might make us feel small and insignificant, but here’s the thing, here’s the big thing, here’s the biggest thing of all: Of the millions of places we’ve ever seen it appears as though Earth is the only place that can support life. The only place! Oh sure, there could be other life-giving planets we haven’t seen yet, but the point is that Earth could easily have been a clump of sulphur gas, be lying in darkness forever, or have a winter that dips a couple hundred degrees and lasts twenty years like Uranus.
GTD is based on storing, tracking and retrieving the information related to the things that need to get done. Mental blocks we encounter are caused by insufficient 'front-end' planning . This means thinking in advance, generating a series of actions which can later be undertaken without further planning. The mind's "reminder system" is inefficient and seldom reminds us of what we need to do at the time and place when we can do it. Consequently, the "next actions" stored by context in the "trusted system" act as an external support which ensures that we are presented with the right reminders at the right time. As GTD relies on external reminders, it can be seen as an application of the theories of distributed cognition or the extended mind .