"Not Supposed To Be A Burden"
Rabbi Dovid Sears commenting on Question From A Reader - An Index Of "Frumness" :
I think your last remark should be addressed first. It might help your shemiras Shabbos to study more about the meaning of Shabbos, in addition to its laws. In English I would recommend Rabbi Aryeh Kaplan's book "Sabbath: Day of Eternity," Rabbi Moshe Braun's "Sabbath Peace," and Rabbi Moshe Mykoff's "Seventh Heaven: Shabbat With Rebbe Nachman of Breslov."
As for the weight shemiras Shabbos is given, Chazal also state that one who observes the Shabbos according to its halakhah is considered as if he kept the entire Torah -- and one who violates it is considered as if he rejected the entire Torah. The Shabbos demonstrates our emunah in a most basic way. Moreover, because Shabbos is the channel for Malkhus / G-d's Kingship, it spiritually connects us to the entire realm of kedushah.
The Shabbos is not supposed to be a burden, but an inspiration and a delight. This is why we are instructed to make the Shabbos pleasant both spiritually and physically by studying the "secrets of Torah" on Shabbos, according to our degree of understanding, by davenning at greater length and more slowly, by eating the best foods, singing zemiros, wearing our best clothes, etc.