There is considerable data about the mental and emotional benefits of journaling. A study by researchers from the American Advances in Psychiatric Treatment noted that writing for 15–20 minutes on 3–5 occasions was enough to help the study participants deal with traumatic, stressful, or otherwise emotional events. It's been specifically effective in people with severe illnesses, like cancer, for example. This practice is so well regarded that there is a Centre for Journal Therapy dedicated to the mental health benefits of regular journaling, both in therapeutic and personal settings.
Some of the most influential people in history kept detailed journals of their lives. These journals served as a permanent record for posterity with the additional benefit of bringing about a much needed cathartic release for the people writing them.
Possibly the most famous journal ever written was penned by teenager Anne Frank; she gained international fame posthumously after her diary was published. She wrote about her experiences of hiding during the German occupation of the Netherlands in World War II. Her diary was incredibly important to her and in it she wrote ‘the nicest part is being able to write down all my thoughts and feelings; otherwise I might suffocate’. Sadly the family was betrayed and her father Otto Frank was the only survivor. Returning to Amsterdam after the war he found that Anne's diary had thankfully been saved; this led to him getting it published in 1947 because he rightfully thought that his daughter’s message was important.
Regularly writing about your experiences not only helps you process them it can also provide more clarity and awareness of any unhelpful patterns of behaviour. You don’t have to create a masterpiece but just writing down what has happened to you will more than likely lead you onto some very interesting thoughts and ideas. If time is limited perhaps you could just write a line a day; it is not meant to be a burden so if you’re unable to commit to daily writing then maybe you could just write a couple of times a week. If you find that you’re really too busy for a journal then you could buy a one line a day memory book or if you prefer to illustrate your thoughts and feelings then perhaps a one sketch a day journal is for you. Also there are 3 or 5 year journals available and some include questions which can act as good prompts if you’re lost for something to write about. It can make for very insightful reading in the future!