In a similar vein, the Kedushas Levi also points out the negative impact of worry and concern, albeit from another perspective. He references the Baal Shem Tov's famous interpretation of the verse 'ה' צִלְּךָ עַל יַד יְמִינֶךָ' (תהלים קכא ה), "Hashem is your shadow [He is] at your right hand", explaining that just as the shadow reflects its possessor's movements, Hashem's dealings with His creatures reflect their deeds. If a person emulates Hashem's attribute of mercy in dealing with others, Hashem will deal similarly with that individual. The Gemara (שבת קנא ע"ב) phrases it thus: 'כָּל הַמְרַחֵם עַל הַבְּרִיּוֹת מְרַחֲמִין עָלָיו מִן הַשָּׁמַיִם', "Anyone who has compassion for the creatures will receive compassion from Heaven". The Baal Shem Tov explains that this principle is also true generally, applying to every kind of behaviour, good or otherwise. And so, a man who practices מִדּוֹת טוֹבוֹת and benevolence, and is happy and content, will find that Hashem will respond to his virtues in kind.
Therefore, the Kedushas Levi says, when an individual places their trust in Hashem, truly believing that their needs will be provided for, they are actively contributing to the fulfilment of those needs from Heaven. Conversely, if someone constantly worries about their financial stability and dwells on the uncertainty of their livelihood, they bring about financial instability for themselves. This is because their thoughts and concerns are reflected by Hashem.
Furthermore, the level of one's livelihood is directly correlated with the strength of their trust in Hashem, much like the relationship between an object and its shadow. Just as a shadow's size is determined by the object it reflects, the extent of one's Parnassah is directly influenced by their level of Bitachon.
(קדושת לוי בשלח ד"ה והנה ידוע)
The Futility of Worry
Once, a troubled young man sought guidance from the Rebbe, Reb Moshe of Kobrin. The weight of life's challenges and financial struggles was clearly visible on the man's perturbed face. Noticing the distress etched on this young man's features, the Rebbe inquired about the cause of his deep distress. While acknowledging the validity of the young man's sadness, Reb Moshe told him that he still has to make an effort to cheer up. First and foremost, because as the Gemara (סנהדרין מו ע"א) teaches us, when a Yid is in pain, the Shechinah, so to say, suffers too. He encouraged the young man to strive for cheerfulness despite his hardships, emphasizing that doing so would not only lighten his own burden but also bring relief to the Divine.
Reb Moshe then offered practical advice, urging the young man to cast away his feelings of depression and assured him that by doing his part and ensuring to cultivate happiness, he would surely witness the assistance of Hashem in overcoming all his problems.
The Rebbe then emphasized that while it is commonly believed that distress can be beneficial, (in Yiddish - צער העלפט) it not only fails to provide help but also has a detrimental effect on both, one's physical and financial well-being. So much so that "עֶס נֶעמְט צוּ הֶעלְפְט גֶעזוּנְט אוּן הֶעלְפְט פַּרְנָסָה" - It takes away half the health and half of the parnassah. (In Yiddish, the word for "help" is the same as the word for "half," suggesting that distress not only fails to provide assistance but also diminishes health and financial stability by half).
Reb Moshe concluded by quoting his rebbe, Reb Mordechai of Neshchiz, who used to say that only one concern is allowed, which should be, "why we are concerned".
(אמרות טהורות קוברין עמוד לה)