Regarding the laws of Shabbat, it is often overlooked that there are two aspects to these laws. The first are the 39 מלאכות that are learned from the construction of the Mishkan. These carry with it very severe punishments from the Torah. One can get סקילה if warned and כרת if not warned and a קרבן חטאת if violated accidentally. The other aspect of laws is learned from Isaiah 58 where the words אם תשיב משבת רגלך come into play. This refers to the idea that our overall demeanor is meant to be different from the other days of the week. The way we walk and the topics of conversation and the emphasis on even having our animals rest, falls under this category. This is where we learn the idea of not doing things that are not "in the spirit" of Shabbat.