The aim of the wise is not to secure pleasure, but to avoid pain.

Reminds me of Charlie Munger's Inversion principle that he borrowed from German mathematician Carl Gustav Jacob Jacobi's man muss immer umkehren. https://fs.blog/inversion/

  We are what we repeatedly do. Excellence, then, is not an act, but a habit.

As counter points, read Cedirc Chin's Problems with deliberate practice, https://commoncog.com/the-problems-with-deliberate-practice/ and Sensemaking as the heart of expertise, https://commoncog.com/sensemaking-heart-of-expertise/

  It is the mark of an educated mind to be able to entertain a thought without accepting it.

This Amjad Masad comment lives rent-free in my head: "Tolerating some amount of cognitive dissonance is one of the best things that I was able to develop in myself ... people don't update their beliefs when new evidence comes to light ... The drive to avoid cognitive dissonance shackles you to your existing beliefs (see confirmation bias)". https://news.ycombinator.com/item?id=11799477 (2016).

cf. Why people that are often right change their minds often, https://fs.blog/some-advice-from-jeff-bezos/