Even if the person is of high standing, and would not ordinarily be seen doing his shopping in the marketplace or supermarkets, nevertheless, when it comes to preparing for Shabbath, he should make the effort do something to prepare for Shabbath. In this way we honor Shabbath. We can learn this from the greatest of our Hakhamim at the time of the Gemara (Shabbath 119a).
Rab Hisda would chop the vegetables very fine. Rabba and Rab Yosef would chop wood. Ribbi Zera would light the fire. Ribbi Abhu would fan the flames. Rab Papa would braid the wicks. Rab Safra would singe the head of the animal and Rabba would salt fish. Rab Nahman would prepare the house and bring in whatever was needed for Shabbath and remove anything that was for the rest of the week. And he would do this several times. This he would do to clearly demonstrate that he wished to honor Shabbath in the way that one would honor and fear one's master who was coming to visit.
From these great Hakhamim we learn that a man must make an effort himself and not say, "It will be a slight to my honor". On the contrary, honoring the holy Shabbath is a man's honor.
(See Sefer Meqabsiel, 2nd year, Lekh Lekha, Oth 6)
Shabbat Preparations, Shabbos, Shabbath