Today, I suppose that your first thoughts of journaling are typing something into a blog, or a word processing document of some sort. That might be fine for you -- there are lots of people doing just that, blogs began as personal journals (web logs).
However, I am going to suggest that a more productive and rewarding method of journaling would be to put pen to paper. Pretty paper, in a bound book (these are so popular these days that you can find nice ones for a buck at DollarTree, much less the beautiful collections at bookstores and places like PaperPosey.com and Rosetti Designs).
1. It's still more convenient than anything with a keyboard.
A paper journal lets you write whereever and whenever you choose to do so. Waiting for the kids, sitting in the car? Write in your journal. Insomnia? Write in your journal. Sightseeing on vacation? Write in your journal. You get the idea.
2. It lets you draw things within your words.
Sometimes, the doodles in your borders or the illustrations within your paragraphs tell you more on the re-read than you realize as it's happening. Lots of dollar signs, guess what's really on your mind? Someone's initials or name duplicated along the margins? Ditto. Also, I've drawn things I don't want to forget -- the bend in a trail that's not marked, etc. -- they may not be true artistic achievements, but they do serve to refresh my memory well enough.
3. You can glue things within the book, making it much more of a memory book.
Movie ticket stubs, wine bottle labels, you name it. As the years go by, these little things make your journal akin to a scrapbook, perhaps even a work of art.
4. Writing a journal is good for your health.
It lessens stress - you can vent as long as you'd like to those journal pages. It seems that writing by hand in your journal somehow not only helps you release inner turmoil and stress by the words you are placing on the page, but also in the physical act of writing them down. It's like a tonic, something that the keyboard doesn't give you. According to some research, journaling actually lessens the symptoms of asthma and arthritis, too.
5. Routinely journaling what's happening in your life has many other long-term benefits.
Keeping your own journal over time becomes chronicling your own personal history. Your vacation journals reveal new things to you when re-read years later, as well as bringing back wonderful memories. For example, I had forgotten how great I thought it was that so many folk in Paris walk the streets with long baguettes of fresh bread popping out of pockets, totes, and bags. No plastic wrap, no lunch bag. Just a loaf of bread, ready to go. Re-reading my Paris journals (I spent some time there, awhile ago), I was reminded. It made me smile.
Personally, I've found it also helps in planning goals, problem solving, and letting go of the past. There's nothing like reading a journal that a few years old to see how far you've come, and to laugh at yourself about how serious you thought a problem was, once - another molehill you assumed was a mountain.
Finally, journaling helps me realize how blessed I am, and what all God has done for me. (And is doing.) Sometimes it's a lot easier to see that pathway of answered prayers when you're reading over those old journal pages, and it's such a wonderful, amazing thing to see your life is on a path, there's a pattern there.