Halakha Mazmur 37:16: Mishneh Torah, Human Dispositions & Kitzur Shulchan Arukh

The straight path is the mean disposition found in each and every tendency of all the human tendencies. Such tendency is removed from both extremes an equal distance, and is not nearer to one than to the other. Therefore have the wise men of yore commanded that man should ever review his tendencies,¹Sotah, 5b. C. estimate them, and direct them toward the middle-path so that he will be sound in body. How may one do it? He should not be an excitable person, easily angered; nor like the dead without feelings, but adopt a middle-course, not to become indignant, save only at something big which is worthy enough to be angry at, so that the like should not be done another time. Likewise shall he not crave for aught save the things which the body requires, and without which it is impossible to be, as the subject is spoken of: "The righteous eateth to the satisfying of his soul" (Pro. 13.25). Likewise shall he not continue to fatigue himself in his affairs, save to acquire what is necessary for him to live on for the time being as the subject is mentioned, saying: "A little that a righteous man hath is better" (Ps. 37.16). He should not be too close-fisted, nor yet squander his money, but give Z'dakah within the means of his hand, and lend accordingly to the needy. He should not be too optimistic and playful, nor too pessimistic and mournful, but spend all of his days in good cheer and with a pleasant countenance. So should he measure all the rest of his tendencies. And this path is the path of the wise men. Every man whose tendencies are mean tendencies of the middle-course, is called wise.

The good and right path to follow is to accustom yourself to walk the middle course. You should desire only those things which are required for your physical well being, and without which it is impossible to live, as it is written, "The righteous person eats to satisfy his soul."²Proverbs 13:25. “To satisfy his soul” means “to keep his soul alive”, in other words he eats no more than is needed to sustain life, certainly no gourmet foods. (Malbim) You should be absorbed in your business affairs only to the extent that it enables you to acquire things that you need for your daily life, as it is written, "Better is the little of the righteous."³Psalms 37:16. Do not be overly tight-fisted, nor spend your money too freely, but rather give charity according to your ability and lend money wisely to whom ever needs it. Do not be too jubilant and jolly, nor too sad and gloomy. But be happy at all times, be contented and show a friendly face. And so too with most other character traits, anyone who follows the middle course is called a wise man.