Keeping a journal has a multitude of benefits and can be so much fun. It's like having a confidant you can tell anything to without fear of being embarrassed or teased or having the past brought up to prove you're something you no longer are.
It's easy, and you can start today. No matter what your age.
Nice quality purchased journal (usually these are made with acid-free paper so that they last), or use any old notebook, if that's what you have. You may use a typewriter and looseleaf paper, or a computer (make certain if you use this option, back it up by keeping a copy on a disk or stick.)
What to write
This is very personal and entirely up to you. You can free-write without thinking. You can set goals and check them off. You can make it very structured like this:
Who and what you prayed for.
What you ate.
What you have learned.
Who you have helped.
What you did that you've been putting off.
What you have learned by reading your scriptures.
What you did that you were afraid of doing.
How you felt about your day.
Anything you write releases what is ricocheting around internally and causing stress-related damage. Get it out and onto paper.
Sometimes just free-writing what is going on allows you to sort through the details and come up with solutions. It helps you to see things as they really are and not as your emotions color them.
Get to know you
Journaling is a great way to really become acquainted with yourself; what you believe in, what matters most to you, and sharing your dreams, goals, and passions.
Don't stew over disagreements. Get them onto paper and work out solutions, then put those solutions to work for you.
Record what you have learned from your mistakes to lessen the chances of ever making them again.
Analyze things that happen around you to determine their impact on you, why they happened, and what motivated them. Make lemonade out of lemons.
Sometimes there are things that happen to you that you could never bring yourself to discuss with anyone else. The first step to healing is to put it down on paper so that you can begin to forgive and heal.
Journals are a great place to plan things that you want to accomplish. In a way, by writing them down you are obligating yourself to actually get them done.
We often receive messages in our dreams. Write them down before you forget them, and then try to figure out what they mean.
This is a biggie. Write down what you learned from your daily study and liken it to your own life. What parallels are there between who you read about, what they are going through, and your own life?
Journal the major events in your life so that you have a point of reference when you get older. Some of these events may be of critical importance at some point, and you will have a record of them to fall back on.
When you look back at something you wrote at 10 or 15 or 20 years old, you will smile at how far you've come, what you've accomplished, and the wisdom you've gained.
There they are, just 12 of the many benefits of journaling. Start today. Just one sentence if that's all you have. Then work up to a daily habit of about 15-20 minutes a day. Learn to love and cherish your journal and share with it the things you can't share with anyone else. It's the cheapest form of therapy around. Take advantage.
Final note: I once had the most amazing friend, Sharon Walker, who wrote daily in a journal for each of her children. I was in awe of her and often thought about how wonderful it would be for children to learn about how their mother felt about them each day; to have a record of every bump and bruise, every giggle and tear, and every ounce of love and devotion a mother can feel. She was pretty hardcore, and I admire her so much.