Journaling is noted by many in the medical profession to be a helpful tool for soul care and healing. This is beyond the simple "dear diary" entries that are associated with teenage girls. The journaling that is proposed as being especially helpful is done with a specific purpose in mind.
Backus and Chapian suggest in their book, Telling Yourself the Truth, that journaling can be used for the specific purpose of identifying and correcting misbeliefs. It is a way to identify and apply truth to one's life. The first step they suggest is to locate and identify the misbelief. This might be something as like this, "People really don't change." The second step in the journaling is to argue against the misbelief. The counter to the belief above might be, "People may not always change in the way I'd like them to, but they do really change. I know I have changed, so it is possible for others to change as well." Thirdly, the key to the journaling is to replace the misbelief with truth. Sometimes the argument incorporates the truth. However, to expand on the first two examples, the third might look something like this, "People do change and are changing. I have been changed. Sometimes it's been slow and painful but I have seen change in myself. I know that God can change anybody. My responsibility is to love this person.
The concept of journaling is not a new one. It is found in many forms of therapy, especially Individual therapy, Cognitive Behavioral Therapy (CBT), and many more. It is not unreasonable to think that it would be just as useful in the Christian counseling session. I know I personally don't do enough journaling, but when I do this type of focused journaling, I am able to acknowledge my own errors in thinking and replace it with truth.