The University of Chicago is blogging about a very neat journal mystery:
Yesterday we received a package addressed to “Henry Walton Jones, Jr.”. We sort-of shrugged it off and put it in our bin of mail for student workers to sort and deliver to the right faculty member— we get the wrong mail a lot. Little did we know what we were looking at. When our student mail worker snapped out of his finals-tired haze and realized who Dr. Jones was, we were sort of in luck: this package wasn’t meant for a random professor in the Stat department. It is addressed to “Indiana” Jones.
This included a handwritten journal penned by Abner Ravenwood, the father of Marion Ravenwood from Raiders of the Lost Ark (and you can read more about the mystery and details of what else came in the package at UChicago's Admissions tumblr blog here.) That someone would go to all the trouble of creating a journalistic homage to a fictitious character doesn't surprise me; writers do it all the time. That they mailed it off to a real university is part of the mystery, as in the film the college Indy worked at was completely invented. My guess is the creator might have once been a UChicago student -- and (obviously) a huge fan of the Indiana Jones movie franchise.
Creating a character journal is much like keeping one of your own; the difference is that you write in character, as this enterprising soul did as Abner Ravenwood. Your dates are your character's timeline, either in backstory or the present (you might even want to explore their future by journal), and any photos, sketches or other visual additions should be character- and story-appropriate.
This kind of journaling can be fun, but it's also serious practice with POV. When you write as your character you have to see things through their eyes, and it can help you understand their thoughts and responses. Before I wrote Evermore I created a poetry journal and a sketchbook for Jayr, my female protagonist, so I could work out her feelings for Aedan mac Byrne, the male protagonist. The project became part of the story, inspired the title of the novel and some of the poetry I wrote in character is actually published in the book, so it was not only immensely helpful, it actually became part of the story.
If you don't want to commit to a project as sizeable as a journal, try writing a letter or a blog post in character. The more time you spend in your character's POV, the better you'll get to know how they think, and like me you may even come up with some fun and valuable story material.