Mental health is the biggest single predictor of life-satisfaction.

And yet, every year, one in five adults experiences a mental health issue. What’s more, the American Psychological Association has found that mental health issues have increased significantly among young adults in the past decade. 

Wherever a person falls on the scale, almost everyone can benefit from better mental health in 2020. As it turns out, one long-forgotten habit from your teenage years may help: journaling.

Studies consistently show the surprising health benefits that come from keeping a journal. Personally, I’ve seen improvements in my own life from keeping a journal for nearly a decade; and professionally, I’ve seen thousands of examples of others whose lives have improved by using my company’s digital journaling app. Drawing on those experiences, here are four ways journaling can help you increase your mental health in 2020:

1. Journaling reduces stress brought on by traumatic or emotional events. Researchers at Cambridge have found that people who spent just 15-20 minutes writing about a stressful event on 3-5 occasions had “significantly better” physical and psychological outcomes. They argued that expressive writing can be used as a therapeutic tool for survivors of trauma.

While not everyone has experienced an event they would classify as “traumatic,” plenty of people experience high stress. Take changing a job, having a baby, going through a divorce or simply playing the balancing act of life, as a few examples. One user found journaling about a stressful job transition provided them a secure place to record their thoughts and feelings about the change, while keeping track of insights and important conversations that helped them get through a difficult time. 

2. Journaling provides a space for positive self-talk and identifying negative behaviors. Researchers have found that “journaling helps focus on one’s inner world, increase positive thoughts and decrease negativity.” 

This was true for one journal keeper who struggled with his use of alcohol. While he admits he never had a “rock bottom” moment, deep down he felt he needed to change his drinking habits. He started journaling as a way to keep track of his habits and make changes, creating “happiness tags” that allowed him to rate his happiness each day. Over time, he noticed a pattern emerge: he was significantly happier on the days he drank less or didn’t drink at all. Eventually, his journal empowered him to make a big change in his life and stop drinking.

3. Journaling helps us prioritize problems and achieve goals.

The University of Toronto found that students who “self-author” — or write down meaningful things that have made them who they are, then use that information to “author” their future — are more likely to stay in school and accomplish those goals than those who do not.

The University of Toronto also found that ethnic and gender-group differences in performance disappeared after two years for students who wrote down their goals.

Writing down what’s important to us — whether it’s what we think about ourselves or what we want to accomplish — gives us greater perspective about what motivates us and helps us visualize what it will take to be successful. Some of our journal keepers have said that keeping a journal allows them to forgive their own failures, acknowledge their successes and, ultimately, “shape a life by design.”

4. Journaling may actually improve your physical health, too. 

University of Texas at Austin psychologist and researcher James Pennebaker contends that expressive writing may offer physical benefits to people battling terminal or life-threatening diseases. His studies suggest that writing about emotions and stress can boost immune functioning in patients with such illnesses as HIV/AIDS, asthma and arthritis. 

In one study, asthma and rheumatoid arthritis patients wrote for 20 minutes, three days in a row. The experimental group was asked to write about the most stressful event of their lives, while the rest wrote about the emotionally neutral subject of their daily plans.

Four months after the writing exercise, 47% of the stress-writing patients had clinically relevant improvement, compared to just 24% in those who wrote about neutral events. In addition, those who wrote about stress improved more, and deteriorated less, than controls for both diseases.

The reason for this, he believes, is that writing about stressful events helps us come to terms with them, which acts as a stress management tool to reduce the impact of these stressors on our physical health.

The mental and physical health benefits that come from journaling are compelling, but even more, having a record of your life, your accomplishments, your trials and even the most ordinary memories is invaluable for anyone. The personal stories listed above came from users of Day One Journal, a journaling app that I founded 8 years ago and has proven to be a resource for millions of people. I’ve become passionate about journaling and making it a part of my daily routine as I record my life as a husband and father of four. Whether you want better physical health or to improve your mindfulness in 2020 — or both — I highly recommend putting “keeping a journal” at the top of your New Year’s resolutions list.