Here are a few ways that have helped me generate ideas on what to write.
1) Write about yesterday's experience
This is the easiest, you just write the chain of events that happened in the last 24 hours. It can get pretty repetitive fast, so it's better to focus on one particular event that stands out. If you want to remember one thing from yesterday what will it be?
Did you work on something interesting yesterday? Share it.
Did you try out a new restaurant? Write how would you rate it.
Did you have a discussion with your colleague on a certain topic? Write your opinion on that.
Are you worrying about something, or pondering some questions? Write about it.
Played a new game? Write about why you like that game.
There are lots of events that happen in a given day, if you pay attention to anything that's remotely interesting, you'll easily get ideas on what to write about the next day here.
2) Commit to learn something
When you commit to learn something you'll read about it and watch youtube videos online on the topic. What ever you've learned can be materials for you to write about.
For example, I wanted to get better at writing. So I learned from books and video courses and wrote a series of posts on how to write better here.
If there's something you'd like to learn, be it sports, how to do a presentation, how to write, how to design, how to code, how to cook, architecture, engineering, arts, anything. As long as it's an area of your interest and you learn something new about it, you can write it here.
3) Check what others have written
This is not an original post idea. @basilesamel wrote the same title how to keep your streak alive on 200WAD, I took that title and write my version of it. There are lots posts written so far on this platform, it may be a good idea to look through them. If there's something that catches your attention and you have a similar experience for, note that down for your next post.
4) Write about what you read
I'm referring to books specifically, not news or other things you read on social media. If you read any book, it probably interest you to some extent.
I think it's a good way to remember what you read by writing part of the story or learnings you get from the book.
I did this a few times and unsurprisingly I still remember what I learn from the book. Like how there's an optimized way for you to poop, yes the one you do in the toilet.