There’s an old (and sad) joke, a commentary on how not to keep Shabbat:
Yankel was in Shul and Berel came to him and asked quietly: “We don’t talk about this on Shabbat but I heard your car is for sale. How much do you want?” Yankel answers: “We don’t talk about it on Shabbat but it’s $20,000. Berel is astounded: “We don’t talk about this on Shabbat but $20,000 is a lot of money… let me think about it…” An hour later at the end of the Shabbat prayers Berel came back and said; “We don’t talk about this on Shabbat but I’ll take it!” Yankel answered: “We don’t talk about this on Shabbat but I sold it already!”
Some people keep Shabbat but their souls don’t get the rest that Shabbat provides. They may be physically resting but their minds are full swing in weekday matters. How are they different from those whose souls also rest on Shabbat?
Rabbi Yaakov Abuchatzeira wrote about this difference explaining that it is mainly in the amount of faith and security in G-d that they feel. If you pay attention to the Torah’s command to keep the Shabbat it doesn’t ‘for six days you should work’ it says ‘for six days work will be done’. It doesn’t say who does it and our sages said that someone who keeps the Shabbat properly will feel that it’s as if someone else is doing the work. If he believes that HE is not doing the work rather that it is getting done for six days; meaning, he works but knows that G-d alone is the source of his livelihood and not his job, then he is the one who can truly rest on Shabbat and it is indeed restful for his soul.
But the one who feels his efforts are what bring his livelihood will never be able to have a restful Shabbat because he’ll feel that his lack of effort over Shabbat directly diminishes his income and this will cause him unrest. This man will keep the physical laws of Shabbat but his mind will still be on the job and not get any rest. He’ll think; ‘this deal I could have done better’ or that deal need to be worked out’…
Only someone who lives with the knowledge that G-d alone is his source of livelihood can easily put up a mental partition and leave work thoughts out of his mind on Shabbat thereby earning his soul its much needed rest. So the best advice to someone is to strengthen his faith in G-d during the whole week then he will find his Shabbat much more restful. This is perhaps why the Shabbat prayer says ‘a rest of truth and faith’ for with faith he can truly rest.
In the book Reshith Chachmah it discusses Shabbat saying that in order to feel the holiness of Shabbat a person must conduct himself properly when working the whole week. If his weekday life is devoid of holiness he can’t change like a chameleon and suddenly seek holiness on Shabbat and he won’t feel its holiness.
The Torah says: “Remember the Shabbat to sanctify it”. Even during the weekdays we should remember the Shabbat and prepare ourselves by adding Torah and holiness into our lives. Then those ‘six days you work’ serving G-d and elevate yourself to “and the seventh day for The Lord your G-d”; you will merit receiving the divine presence and the exalted holiness of Shabbat!