I have ONE GOLDEN RULE for capturing new ideas.
I never capture an idea without doing a quick brain dump.
Did I mention... Never
An idea is always freshest the moment it sparks in your brain. And that is the time you want to capture the essence of it. Don't worry it won't be pretty & it will probably look like word vomit, but it will contain the spark.
Sure, it's not always convenient to take the time to do a brain dump. I remember having to pull over on the side of the road and brain dump a big idea I had about the difference between shy people and introverts. And don't get me started on the number of ideas I have while swimming in the ocean.
When it comes to capturing. My tools of choice are:
Notion if I'm at my computer or have my phone
Otter.ai if I'm out and about and I can't type.
Apple Watch Voice capture for when I'm out in the ocean
If all else fails... the back of a napkin.
Pushing yourself to get the idea captured and some words dumped about it in the moment means you can experience the magic later. You'll never have to sit down to a blank page again when you write. At worst you'll have a sentence, at best you might have a whole essay or some bullet points.
Try it out for the next week and see if the friction in your writing is eased just a little.