Quote Originally Posted by ArcCaster View Post
So, can I conclude that executing a task requires a fraction of the brainpower that planning does? And vice versa, that planning is an order of magnitude more difficult than executing?
I assume it varies. As I see it: The only thing we use our brain for is planning.
Actions are done by muscles. However, some of the planning occurs during the
action. If you're a basketball player, stock-market-floor trader, emergency room
physician, air traffic controller etc. you're not going to plan your specific actions in advance.

In GTD (as I see it), the planning you do during the action counts as part of the action. So it might be easy to plan "Be on the basketball court by 2PM",
and yet take a lot of brain power to figure out where and when to throw
the ball once you're there. The GTD "action" could be "play a basketball game":
actually many small actions, but you wouldn't write them as individual
actions in your GTD system. You could be tired when you agree to play
and mark it on your calendar, and then want to make sure you rest and eat at the
right times to be at peak mental performance while playing.

Or, for some things, the planning in advance could be much more difficult
than the thinking you do during the action. Or, they could be comparable.

Often, an action involves about 2 to 10 seconds of serious thinking before
you start moving. Once you start moving, you've pretty much committed
yourself to doing the action now, and you'll probably continue even if it
involves some more serious thinking along the way. But doing 1 second
of the original thinking doesn't really commit you to continuing.
That serious thinking can be a barrier. It might not take a large amount of
effort, but it takes enough effort that it can be easier to think "I'll
decide later".

One of the brilliant things about GTD is that you get
that 2 to 10 seconds of thinking done in advance, so when you're
considering doing the action now, all you have to do is start the actual
action, which takes much less mental effort to get started -- and
then you're physically moving, so you have momentum.