This Shabbat we read Parashat Tzav. The word "tzav" is an imperative form of the word which also gives us "mitzvah." Therefore "tzav et b'nai Yisrael," the first phrase in our Parasha, means "command the Israelites" or even "proclaim a mitzvah to the Israelites." The Torah is full of mitzvot but the formula "tzav et b'nai Yisrael" does not appear that often. Usually it is "vayidaber Adonai et Moshe l'emor" -- God spoke to Moses, saying. Why here is it "command" and not just "say"?
Rashi writes: "The expression “command” always implies urging ("ziruz") one to carry out a command and also implies that the command takes effect at once and is also binding on future generations. Rabbi Shimon said: “Especially must Scripture urge the fulfillment of a command in cases involving financial loss.”
It may be that the reason ziruz, urging, was so necessary here was because the commandment concerned the bringing of the daily sacrifices, which were to be brought twice daily for all eternity. Inasmuch as this would require the expenditure of vast sums, some hesitation might be expected. However, in the case of other mitzvot, e.g. lulav, even though they require expenditure of money, it is limited, so the Torah does not use the word tzav in connection with such commandments."
Rashi shows a recognition here that Jews may not always be enthusiastic to fulfill the mitzvot. Of course here there is a rational basis for the reluctance -- it's expensive. And the fact of the matter is that financial issues were often a challenge to fulfillment of mitzvot -- but the halacha tried to evolve to accommodate external reality. For example, the selling of chametz before Passover was developed because of Jewish distillers and liquor merchants who found it impossible to literally dispose of their entire inventory for Passover.
But of course there were limits. Late Friday night services were an American invention. In the old country services were held Friday evening at sundown, not at 8 or 8:30 pm. But in America in the early part of the 20th century, people had to work on Shabbat. Business put up signs that said "if you don't come to work on Saturday, don't come to work on Monday either." But no one ever explicitly said it was OK to work on Shabbat.
Today the disincentive to observe mitzvot is rarely financial.Jews in prior generations went to work on Shabbat because they really had to -- there was no legal protection for religious observance and there was a legitimate issue of survival. People felt that they were doing the wrong thing but felt they really had no choice. Although there were people who made the sacrifice, they knowingly chose poverty in order to observe Shabbat. But today for the most part nonobservance is through choice, not necessity.
If something is a mitzvah we can deduce two things about it. One is that we would not otherwise do it; the other is that we can do it. God doesn't waste time commanding is to do the self-evident but neither does God command us to do the impossible. What's yourreason for not observing some of the mitzvot you currently choose not to observe?