Just the act of turning the page to a new sheet of paper (or opening an empty note on your computer) and staring at the screen makes you write. Don't say it doesn't, cause it's just not true. Just pause and keep staring withoug doing anything, you will write. Maybe not right away, but with time it will come. The key is not to do something else when you're stuck without anything to write. It is easy to take your phone in search of ideas, for once don't.
Maybe it will be some rubbish like this, but just maybe it will be something more meaningful. But you will write.
Don't force it
If after a while it looks like you're not getting anywhere just save the note and come back to it in a few hours, it might be helpful to come back to it with a somewhat fresher look.
Don't force a topic if it doesn't come up, just write and see where it brings you. It might surprise you, it often does it for me.
Writing is hard, it might seem easy at times, but whoever says it's easy hasn't been doing it for long enough. It is really satisfying and a craft worth pursuing.