Getting Things Done, the famous task-management methodology created by David Allen in his book, Getting Things Done, can be summed up in three words: “Mind like water.”

The idea of GTD is to get everything out of your head, and into a system you trust. Whether it’s online, on paper or something in between, the point is to create a system you believe in and buy into, and never trust your memory again. Put things into your system, and know they’ll be there when you need them, and present themselves when they’re supposed to. Then, your brain is free of other pressures, and able to be what you need it to be.

GTD is tremendously applicable to people’s work lives, but also in life outside of work. The “mind like water” principle is one that can, and should, be applied to every aspect of our lives. When we’re not preoccupied with things, not thinking about the same things over and over, we’re able to be more in the present, more available to those around us, and more productive in all that we do.

That’s why all GTD practitioners should keep a journal. Your journal should be for your personal life what your moleskine or task manager is to your professional life. Keeping a journal allows you to get thoughts out of your head, into a different location, and lets you not be preoccupied with the same things over and over.

With journaling, you also need to create a system that works for you. For a long time, I kept a journal full of one-sentence memos to myself that I wanted to remember, typically based on some revelation I would have at the most random of times. Then, as I began to write more and more, I started to keep a more traditional diary-type journal.

I’m able to get thoughts out of my head and onto paper, and there’s something cathartic about having my thoughts written down. I even go back over my journal every once in a while (Weekly Review, for the GTDers) to see what I’ve been thinking and where my brain’s been.

Instead of keeping thoughts in, and having them dominate your mind, a journal lets you get it out and then not think about it- not letting one thought dominate your time and attention is key to GTD. With personal issues, this is obviously not as simple, nor as cut and dry as it is with work tasks, but it’s a useful tool to keep your mind empty, your thoughts clear, and your focus on the worthwhile.

If you’re looking to become a journaler, and want to do it online (as I love to), try Penzu. Penzu is a basic, easy-to-use online journaling software that I find really useful.

You just log in, and start writing. Things are saved, secure, printable, exportable, and accessible for you. I love having my journal online, because it lets me journal whenever and wherever the opportunity and inspiration strikes without having to carry a big notebook around with me.

Journaling has been great for my head, great for my GTD practices, and great for me personally. I highly recommend it, and following GTD is nothing more than an excuse to start what, I think, is an important habit for anyone.

A journal can be anything for anyone- use it as a memory-preserver, or a diary, or anything you can think of. A friend of mine kept a journal full of photos, a timeline of important events in his life. Whatever your journal looks like, use it to get your thoughts out of your head, and make room for some new ones.