As with all types of journals, you need to adapt what you do to meet the requirements of individual students. Having students work in pairs or small groups at different times often helps those who have difficulty making entries in their reading journal. Most authors keep a writers' notebook of some kind in which they jot down their observations thoughts and feelings, stick in interesting bits from newspapers and magazines, write down snippets of conversation they have heard, all of which provide a stimulus for writing. Students can do the same thing. Ask visiting authors to bring along their writers' notebook to share with students.
Many authors use their writer's notebook to engage in free writing.
Free writing enables them to engage in the act of writing and lets thoughts and feelings flow. Although they may not immediately use the free writing, they can go back to it for inspiration at another time. Suggest that students keep their notebook handy and record the date of each entry. In time, students will build up a treasury of ideas and experiences to use later. Like professional writers, they can pick things out, change them around, adapt them and polish them for publishing.