I journal or make notes daily (I got into the habit in 2013 during my first marriage when my spouse was a drug addict), and I currently use Apple Notes as I almost always have access to my iPhone or iPad. I have used other applications in the past (Evernote, Outlook). Sometimes I put down a lot, sometimes it's nothing more than "ugh" or "sigh" followed by a quick note of what it was.

And I do use a template each day, broken into three main sections:
Daily Notes:
What went right?
What could have gone better?

The notes section is where I write down everything and anything. The other two sections are for short bullet points ( "I exercised today!", "I am stress eating 🙁 ", "Person X upset me, grr") so I can go back at the end of the week and skim over them to review my accomplishments, trends, or areas I need to focus on to improve.