"Aphorismen zur Lebensweisheit" by Arthur Schopenhauer is an essay published in 1851 as part of his work Parerga and Paralipomena. Departing from his metaphysical philosophy, Schopenhauer offers practical guidance on living less miserably in an imperfect world. He divides human existence into three categories: what one is, what one has, and what one represents to others. Emphasizing personality, health, and temperament above wealth and reputation, he explores the art of making life as agreeable as possible when true happiness remains beyond reach.
Wikipedia page about this book: fr.wikipedia.org/wiki/Aphorismes_sur_la_sagesse_dans_la_vie