>> Anecdotally, I've known someone who used to be stressed out and controlling. Last time I saw him he was not so stressed. He said his life changed once he surrendered and accepted his destiny. He didn't go religious or anything, just 'accepted' his fate.

The stoics called this "Amor Fati" - Love of Fate (which admittedly is a maybe a step beyond your friend): https://dailystoic.com/amor-fati-love-of-fate/