Here is an update.

The person got actually very excited about GTD and I gave him another book too, getting things done.

He also told me that he got really interested after he saw me using gtd and still staying very efficient and moving multiple projects forward while also beign very tired and brain dead because I haven't slept for 24 hours (I was adjusting to a new sleep schedule)...
I told him that I dont have to re-think stuff all the time, I have to think only once ideally, so I stayed efficient because all the thinking was already done previously when I had high energy