By writing it in your own words.
Write what you understood, by watching or reading something.
It will become your own this way.
And you will be able to use it easily in your life, in your presentations, conversations, and in your business.
It is easy to do with books and videos.
If you are reading on a Kindle, then to avoid breaking the flow, you can highlight a section, leave yourself short notes while reading and come back later to write the note.
Same with videos. Note the timestamp, and write 1-2 lines on what you learned and then come back to it and expand those 1-2 lines. If the need is, watch a section again and then write your note.
When following this approach, you may be able to watch fewer videos or don’t read as many books as you would if you didn’t summarize and take notes in your words, but you’ll retain more.
Isn’t that the goal when we are consuming content to learn and grow?