Thanks for your reply, Smarky.
But I think that you misunderstand the concept of the GTD system.
Yes, it's a "huge" system to write down a to-do list, but that's not all there is to it.
It's purpose is to empty your mind of the countless things you think about so that you can spend your time without having to stress about things that you want or need to do in the future.
It also saves every good idea that you get. By not using the GTD system, many ideas which could have great potential will just be forgotten.
It sort of moves the practical planning / remembering section out of your brain so that you've got energy / room to enjoy yourself.
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By implementing the most important parts of GTD into a small notebook, you avoid ending up with countless folders and GTD system stuff in your home.
All you need is your notebook.
The reason for me to choose the Moleskine for this is that it's really nice. Makes me want to write in it.
And the fabric bookmark is a very nice feature also.