We all write in our daily lives with emails and texting, etc. But journaling is different. Many things you read would have you believe it's only for self discovery. But journaling can be helpful in many ways. This article at Psychcentral.com suggests that journaling has many heath and emotional benefits.
I did lots of journaling when my kids were growing up. Mostly so I could remember things that happened! Some things I journaled about were happy, some sad, some maddening! Sometimes I only had time to write a sentence, so I could come back later and expand on the subject. I remember in school, the kids would get journaling assignments and find it so hard to find things to write about. They seemed to think these entries had to be about exciting or important things. I tried to tell them that they didn't. It could just be about something you were wondering about that day. Or telling about a conversation you had with someone. So I understand that you may find it hard to start journaling. 
We found these journals that help with that. They don't just have plain pages. They have prompts, which help you get started writing. They also have plain pages where you can expand on a story if you get on a roll!
Perhaps you could start during a vacation when you have plenty to see, do, and write about. It's a great way to have the kids sit and reflect on their summertime trips and activities too! We have lots of subjects for your own journaling or to give as a thoughtful gift. You can buy online as a gift for someone you know here.