Because It’s Challenging
Unplugging, eating wonderful meals, connecting with family and community — these things require discipline and preparation. Also, calming one’s mind, choosing to miss out on the hubbub of the outside world, and taking a pause.
It also takes effort to learn prayers and pray with kavanah (intention). Shabbat is not simply a holiday that happens to us, it’s one we make happen, and sometimes doing so is quite difficult. One reason to make Shabbat a part of one’s week is not because it is easy (though taking a nap on Shabbat might be deliciously so), but because it is hard.