This habit of writing a journal can be life changing, and once you get into it, this will remain with you forever as it empowers you to live true to yourself. Also, it's very interesting to go back and read your own thoughts, feel the emotions you felt at the time and find out how far you have come and how much you have grown as a person.
Take it as a research project on yourself, observe your actions, feelings so you can get to know yourself better. Trust us, this is the most liberating feeling ever.
How To Start a Journal:
You don’t have to be a professional writer to learn how to journal. However, if you feel you can only write in a certain ambiance, then go ahead: give yourself a corner in the house where you feel most at peace, light a candle, pick the writing tools of your choice, play soft music and dive right into it.
Pick a topic that you want to write about, it can be anything from your day-to-day routine to anything that's making you think lately. Give yourself a time of 15-20 minutes and while writing let your thoughts flow, just keep writing without any interruption, don't worry about editing, spelling mistakes, just let it all out on that piece of paper. You can edit it after you're done writing.
This can be your 'me time' and a great time investment that you will certainly thank yourself later for. So pick up your tools and get right into it to know yourself better.