I’ll add to this periodically.
“There is no merit in being patient and good-tempered when there is nothing to irritate you.” ~Emily (Maria Susanna Cummins, The Lamplighter)
“The more decisively you adhere to a manly simplicity in your dress, equipage, and behavior, the more you devote yourself to business and study, and the less to dissipation and pleasure, the more you will recommend yourself to every man and woman in this country whose friendship or acquaintance is worth your having or wishing.” ~John Adams to his son John Quincy Adams. (David McCullough, John Adams)
“You cannot prove to yourself that you love God by examining your feelings towards Him. They are indefinite and they fluctuate. But just as far as you obey Him, just so far, depend upon it, you love Him. It is not natural to us sinful, ungrateful human beings to prefer His pleasure to our own, or to follow His way instead of our own way, and nothing, nothing but love to Him can or does make us obedient to Him.” ~Dr. Cabot to Katherine. (Elizabeth Prentiss, Stepping Heavenward)
“It was not in her nature, however, to increase her vexations by dwelling on them. She was confident of having performed her duty, and to fret over unavoidable evils, or augment them by anxiety, was no part of her disposition.” ~Narrator, speaking of Elizabeth Bennet. (Jane Austen, Pride and Prejudice)
“Half the misery in the world comes from trying to look, instead of trying to be, what one is not.” (George MacDonald, The Flight of the Shadow)