Cool! I use DIscourse this way for myself too, and I love it.
Discourse for Teams provides a weekly update topic for each member of the team. It is generated automatically each year and the team member can then add replies each week. If they forget, they are automatically sent a reminder.
With Discourse you can also use various features to make it easy to keep a journal. For example using topic templates to set up a category so new topics have some info prefilled. I also like Discourse-reply-template-component which lets you add a reply automagically with some info prefilled - it supports dates as well. Then add a bookmark with a reminder for when you want to next add a reply, and you’re golden. 