>statements like "she succeeded 'cause she was tough" are meaningless as advice or actionable/verifiable statements

The action you are supposed to take from this is to figure out whether you're tough, and if you find out you're not, to give up and go to something else you're better suited for. This seems like exceptionally actionable advice - just not advice that strokes anyone's ego.

I will give you an example. When I was 17 I spent exactly one day as a door to door canvasser for an environmental charity. I got dropped off into a neighborhood I had never seen before, told to walk up to people's doors and beg them for money for something I was pretty sure wasn't particularly effective at solving anything important, and then do this about a hundred times.

Door #1 gave me one dollar. Door #2 let me call my parents in tears to come pick me up. Whatever Unusual characteristic that particular job needed, I did not have it. I do not have it to this day.