I think the biggest "learning" from running 90mpw for 2.5 years is a realization of how "you can just do things," and just getting started gets you >50% of the way there

e.g. it sounds obvious, but I didn't realize the way to run 90mpw is just... to go run 90 miles

continuing on the running example: I think most people stress over a bunch of nonsense that doesn't matter as much as they think (especially at the start) like injury prevention, how to "properly" train, types of shoes to run, fueling/hydrating, etc.–just go run

partially agree on this. running 90mpw is not for everyone. you cannot just go and start running 90mpw... you can just go and run (as I've done 10 years ago) but the mpw you eventually reach is very different from person to person.