At Shalosh Sheudos on parshas Vayakhel, Rav Moshe Weinberger spoke on a fundamental point that especially working people have to internalize. I will (freely) translate the piece he quoted from the sefer Shevet Sofer by rav Simcha Bunim Sofer, the grandson of the Chasam Sofer, on Vayakhel, and then I will (freely) translate a piece from Likutei Halachos that my friend Dov Perkal pointed out to me which makes the same point.
"Six days work shall be done and the seventh shall be holy to you, Shabbos Shabboson..." (Shmos 35:2) (emphasis added)
The pasuk earlier said "remember the Shabbos day to sanctify it... and you shall call Shabbos a delight." (Shmos 20:8). However, there are those who does not believe with perfect faith in Hashem that everything comes from Him, and that a person's livelihood is fixed and that it is Hashem who gives a person strength and success. Such a person will be somewhat sad on Shabbos, and he will not rejoice in Shabbos, because his heart will be filled with worry, thinking that he is losing out by desisting from his efforts. Therefore, one must believe that everything comes from Hashem, and that "bread is not for the wise and neither is wealth for the discerning" (Koheles 9:11). Rather, [a person must work, as it is written,] "in order that Hashem your G-d will bless you in all the work of your hands that you do" (Devarim 14:29).
Hashem wants a person to do what he is able to do and not to rely on miracles. But nevertheless, one must know in his heart that everything comes from Hashem, and that without the blessings of Hashem, nothing he does would have any effect and all would be for naught. If a person has belief in this fact, then he will certainly rejoice in Hashem and Hashem will give him everything he needs during the six days of the week, just as it was with the manna, which Hashem gave as a double portion before Shabbos.
Similarly, with regard to the Menorah, we also find that Hashem said to Moshe, "As one piece it shall be made..." (Shmos 25:31) (emphasis added) The Medrash explains why the verse says "it shall be made," rather than "you shall make." It says that that it is because Moshe had difficulty making the Menorah, and toiled greately until finally, he could not make the Menorah. Once Moshe had difficulty, Hashem said, 'Take a meausure of gold and throw it into the fire, and then it will be made by itself.' This is the meaning of the phrase 'it shall be made.'"
A person's work life must be the same way. A person must work and toil, but nevertheless, he should not say that "my might and the power of my hand has made all of this success for me." Rather, he should view it as if everything happens without any effort of his own through the blessings of Hashem, and as if he did not do anything."
Reb Nosson in Likutei Halachos Orach Chaim Hilchos Shabbos 3:4, 7 (quoted above), commenting on Shmos 25:31 (quoted in the Likutei Halachos Chumash):
A person who does business and work, must subjugate all of his thoughts, actions, and words to Hashem ... and to believe with perfect faith that man alone accomplishes nothing whatsoever. Rather, we are obligated to do some business and work because it is Hashem's will that we do so, since there are deep secrets and great intentions in every aspect of business and work. This is because through work, one can accomplish great clarifications and draw holy sparks through his work and toil, as is known. For this reason alone, we must at least do some amount of work or business because it is Hashem's will. It is for this reason that the sages said, "Torah is good if it is with the ways of the world."
In truth, though, a person does nothing at all. His livelihood does not comes from his physical activities at all. On the contrary, his main livelihood comes from abstaining from the 39 forms of labor on Shabbos. This means that the illumination of Hashem's will, which is the aspect of the holiness of Shabbos, is the source of the blessings of the six days of the week...
When we merit to do business and work in this way [of remembering that all the results and income that we receive come from Hashem and not as a result of our efforts], even though we do work, it is not considered "doing" anything at all. Instead, it is an aspect of our work being done automatically, on its own, as the pasuk says with regard to the Mishkan, "the Mishkan was erected," and the Menorah shall "be made."
It is amazing to see the confluence of the same teaching from the non-Chassidish world of the Shevet Sofer and the Chassidus of Rebbe Nachman/Rebbe Nosson when they both come to teach us the same lesson. If we are zoche to mentally separate our efforts from the income we receive, then we will truly have oneg, happiness, and really be able to keep Shabbos without worrying about the work that we still need to do.
IY"H, may we all be zoche to repeat this truth to ourselves, internalize it, and live with it throughout the six days of the week and Shabbos kodesh!