This is an evolving post. Keep checking back in, we'll add more reasons over time. Let's see if we can make it to 100...
1. Writing spawns clarity
The very act of writing things down forces us to bring complex thoughts in order. In many cases this will lead us to the realization that we have no clue about some of things that we thought we had figured out. Likewise, some problems might turn out to be easy to resolve or rather opportunities than problems.
Looking back and assessing your experiences and decisions with hindsight is an essential ingredient of improvement and progress.
3. Keeping a record
It is in general amazing to possess a record of one's life. Image you open your journal 10 years from now and read about what you did today. Sometimes it is also valuable to be able to reconstruct how events unfolded in great detail.
4. Improving memory
Forcing your brain at least once every day to recollect details about what happened will train the gray matter and make it better at this task over time, thus gradually improving short-term memory.
5. Surfacing monotonous behaviour
Almost everyone would agree that it is boring to do the same things over and over again every single day. Yet, it is easy to adapt a very monotonous lifestyle without being actively aware of it. Keeping a journal will change that.
6. Incentive to do something special
Elaborating on #5... being forced to write down what you did on every given day might incentivize you to do small things that make the day special and worthwhile, even if it is just for the sake of having something interesting to log.
7. Taking things off your mind
It's a common practice to write "loud" thoughts down to take them off our minds. That is also why many people like to make lists. Once something is written down or expressed our brain usually drops it from the repeat loop.
8. Tracking habits
Tracking both good and bad habits is a great strategic way of reinforcing or getting rid of them.
Some journaling apps like Journalistic make habit tracking very easy with tags and visualizations.
9. Disecting decisions
If you ever look back and wonder why you made a certain decision that makes little sense in the now you can look up the days that preceded the decision and reconstruct your train of thought based on the events that occured.
10. Assessing the state of your life
Am I happy? Do I make progress? Am I on track to achieve my goals? Those are at least partially subjective questions and the answers might vary from day to day. But it might help to have a look at the big picture and look at actual numbers, e.g. how many highlights did I mark in my journal per week, what is the ratio of positive to negative entries, aso.
Journalistic is currently conducting research on whether it is possible for algorithms to assess happiness over time automatically from your writing.
11. Auto-biography material
If you ever become famous and want to write down your memoirs, a journal is invaluable to fill in the gaps in your memory. Just kidding...
12. Analyzing changes
It is easy to fool ourselves when we assess situations in hindsight. To accurately analyze a change it is favorable to have a written record of details over time. For instance, if you decide to stop smoking or start to meditate on a regular basis your journal will reflect whether or not those changes had an impact on your life and also how long it took for the change to take effect.
13. Tracking relationships
"Where did we actually meet?", "How long have we not seen each other?", those are questions we all have asked and their importance can range from "fun fact" to closing a business deal or not. Marking social interactions in your journal can help with these questions.
14. Writing daily improves your ability to express yourself
Many people are not as good at expressing themselves as they could be and the reason for that can more often than not be found in a lack of practice. Expressing yourself usually comes short in modern-day life and we receive more appreciation for just going along with whatever society dictates. Keeping a journal is a great way to practice. Expressing your thoughts daily in written form can work magic in making you better at expressing what you really feel or want.
15. Gratitude is a powerful tool
Psychology research shows time and time again that the plain act of being grateful increases happiness. Simply thinking about your little privilegdes sparks positive emotions and measurably improves mental and physical health. That is why so many journaling apps leverage this ancient technique.
16. Browsing through old entries is fun
Sometimes is just fun to flick through your journal and skim over old entries.
17. Routines are great for rhythm
Daily routines are great, they are like anchor points for our mind to adjust by. Many of history's greats are known to have adhered to routines to stay on track. Journaling is an easy and useful routine to establish.
18. Collecting wisdom
How many times have you learned something very valuable but forgot about it later? A journal is a great place to store 'learned lessons', 'deep insights', etc.
19. Staying on track
When writing about your daily business frequently it's very easy to assess whether you are locked in on pursuing your goals or not, whether you make continuous progress or constantly get sidetracked by things that neither bring you forward nor give you joy.
Thanks for checking in!
If the above list inspired you to start a journal check out Journalistic and sign up for free.