Unless he found some secret magic trick, I believe they have in general been written down already a millions times by now. And yes, they have to be hard earned, meaning when you do carry your big backpack around way longer than you planned for (because a bus was not there or whatever) - you do learn to not appreciate all the useless things you carried for no reason and leave them at home next time.

Best advice:

Travel light

But still, mind where you are going. If it is the mountains, you still want to bring warm clothes and they just are heavy.

I am right now preparing for the mountains and think of whether to take a tent or not (the huts for sleeping are mostly closed already)

The heavier the backpack, the less fun is walking with it.

And that works also as a metaphor for everyday life. The less shit you take with you, pulling you down, the easier it is to make progress.