Open the Journal app on your iPhone. Tap Recents to see the suggestions ordered by the hour. Tap and then look for recommended suggestions. I think the application in general is a start to something great, but currently it seems a little incomplete. When looking for suggestions, you'll see two tabs.
The Recommended tab shows content over the years, such as photos, videos and locations, to inspire you to write about a memory. In between, there are Reflections, which consist of introspective suggestions such as “Write about a time someone did something special for you”. Include a photo of the same. Or “Describe the most memorable part of your week.
The Recents tab shows suggestions for your daily activities throughout the week, such as the phone calls you made, the photos and videos you took, or the places you went to in an attempt to inspire you to write about them. If you are already in the habit of keeping a diary with a physical notebook or you regularly use another application to keep a diary, I wouldn't change it, unless you really want to incorporate content from your phone or you often have difficulty knowing what write.