People struggle to write because they sit down in front of a blank page and try to come up with a brand-new thought on the spot. This is a recipe for frustration.
Instead, you should look at the places where you have already been writing: your notes, your emails, your Slack messages, real-life conversations you’ve been having with people, etc.
You have plenty of material already: you just need to sit down, collect it, and give it a sense. That’s the core of the Zettelkasten method.