If you're reading a print or hardcover book, write your notes and highlights into a word processor or note-taking app.
If you're reading a Kindle book, add your notes, then export your notes and highlights. Copy them into a preferred word processor or note-taking app. Remove all the irrelevant markings, like "Read more at location {NUMBER]", "Add a note".
Now, rewrite each highlight in your own words.
If you highlighted chapter headings, change them into subheadings.