In comments to my last post, I said that one of the proposed strategies in dealing with the world is “to recognize that in our lives, there are Jewish needs and there are regular, human needs. Just make sure they don’t contradict (and if they do, figure out, what’s more important in [each] case — and if you can choose a more lenient way in Judaism to accommodate a conflicting ‘worldly’ need, then do so).” Chabad Chassidus rejects this approach. Why? What’s wrong with a compromise between stringent and lenient, between Judaism and the worldly pleasures? The Lubavitcher Rebbe’s sicha on parshas Lech Lecha discusses this question.
Torah (whose name means “teaching”) provides an everyday lesson for us. Of course, Torah is the source of Halacha which governs our everyday life, but what about the portions of Torah that are not related to specific laws (or the immediately applicable laws)? The answer is that Torah that we see is only one dimension of the whole Torah. Stories and even laws presented in it hint at processes that happen in the spiritual realities of the Universe, whose study concerns us everyday and reveals more general themes of our service of G-d and life. Lech Lecha teaches us the meaning of “going away”, out of one’s current situation, one’s current bounds, for the sake of elevation.
One may think this means physical bounds and even spiritual bounds. No, says the Rebbe, it included the bounds of Torah, holy bounds — these also need to be broken, in order to go higher than one’s current position.
[E]ven before the circumcision, and even before the command to  “go forth from your land,” Avraham Avinu was at a lofty level. In the words of my revered father-in-law, the Rebbe [Rayatz], in the sichah of Simchas Torah, 5710  , Avraham Avinu was then a Jew of 75, master of many estates and master of all areas of his conduct. He had attained all the levels that he could have possibly attained by his own efforts, including even the level [in the apprehension of Divinity] known as  shekol hane'elam mikol ra'ayon.
And at that point he was commanded to “go forth from your land” i.e., to elevate himself to an even loftier level, and then he was commanded further concerning the circumcision. From this we may gain some notion of the sublime level which his circumcision enabled him to attain. […]
The mitzvah of circumcision elicits a flow of divine lights so sublime that they utterly transcend the created universe and Seder Hishtalshelus, the chainlike scheme of orderly descent by which divine light is progressively contracted. […] Furthermore, the mitzvah of circumcision upgrades the individual out of all proportion to his former spiritual state — like birth. [...]
As a preparation for the circumcision (which signifies a birthlike revelation and elicitation of sublime spiritual lights), Avraham Avinu was commanded: “Go forth from your land,” and so on. I.e., in order to arrive at the level of such lights, he first had to step out of his present bounds, even holy bounds.
The way to break out of the bounds and restrictions imposed by the animal soul is to conduct oneself according to the Shulchan Aruch and to study ethical writings. This enables a person to realize that materiality is utterly worthless . As a result he will free himself of the restrictions of the animal soul, and of course from the restrictions of the body. However, when it comes to freeing oneself from restricting bounds in holy matters, that's quite a different story.
Exactly what are the latter restraints?
Concerning the study of Torah a man might argue: It’s enough for me that I am one of the  “supporters of the Torah”; it's enough that I study  “one chapter in the morning and one chapter in the evening”; the shiur after davenen will suffice; studying without exerting the soul or the flesh will be quite enough; it's enough that I study nigleh, the revealed plane of the Torah: do I have to study Chassidus as well?!
Concerning avodah, i.e., davenen, the same individual argues that it's quite enough that he arrives at shul in the middle of davenen; according to the Shulchan Aruch he can then skip most of Pesukei DeZimrah, the psalms of praise — i.e., three-quarters of the davenen — so long as he prays together with the congregation . Surely it's enough that he hastily churns and chops his way through the words , without taking time off to think what they mean . If he does think about what the words mean, without meditating for a moment on Whom he is addressing , then surely that's more than enough. As to the earnest frame of mind  that is supposed to precede prayer, he discharges this obligation by clasping his hands like a servant before his master; now, having done that, he can allow his thoughts to fly hither and thither...
Concerning tzedakah, this individual argues that the Shulchan Aruch  itself lays down limits. There is a certain quota required by the Torah, deoraysa, and there is a certain quota required by the Sages, deRabbanan — and surely he is not obliged to give away more than the prescribed minimum. As to giving away more than a fifth of his income, then this is not only not obligatory, but (he argues) forbidden! For did not the Sages say that “he who gives freely should not give away more than a fifth” ?
Besides, this individual argues, in no area of his life should a man make more stringent demands on himself than the Torah requires him to. For this stance he quotes the Talmud Yerushalmi : “Let the Torah's prohibitions suffice for you!” “Tell me,” he protests, “am I expected to be more pious than the Yerushalmi?!” In similar vein such a man contends that it is not proper to expect him to do things that go beyond the letter of the law : if only he would conduct himself according to the law, he says, according to the Shulchan Aruch…
These arguments derive from the limitations of one’s mindset — including the limitations of one’s mindset in holy matters.
Next, explaining the statement in Gemara “an ignoramus is forbidden to eat meat”, the Rebbe talks about the revolutionary understanding of Chassidus of the role of a Jew’s life in this world, the mission for which his soul descended into this world, so that it can ascend. He also discusses why even things permitted by Halacha need to be avoided, if they don’t serve a holy purpose directly.
My revered father-in-law, the Rebbe [Rayatz], once remarked  that in America there is an illness called “you're allowed to”.
On a number of occasions, by way of contrast, he related that chassidim are accustomed to say : “What you're not allowed to do, you're not allowed to do, and what you are allowed to do, you don't have to do."
Along these lines it is taught that “an ignoramus is forbidden to eat meat.” This does not signify an actual prohibition , for something that is actually forbidden (assur) is irredeemably bound (assur) in the clutches of the kelipos , and one cannot pronounce a blessing over it. In contrast, meat eaten by an ignoramus is not bound in the clutches of the kelipos; moreover, the ignoramus is obliged to pronounce a blessing before and after eating. Rather, the brakes applied above to the ignoramus echo the traditional advice: “What you are allowed to do, you don't have to do.”
Chassidus discusses the question  of whom eating is mainly intended to benefit. Eating is not primarily intended to serve the needs of man by enabling him to be a recipient and derive his nourishment from it, for man's spiritual standing is higher than that of the food he eats. Rather, eating is mainly intended to serve the needs of the food. The food desires and waits for man to eat it, so that he can sift its materiality and discover the divine sparks embedded in it and thereby elevate it.
In this spirit my revered father-in-law, the Rebbe [Rayatz], once related that one day a morsel of food fell from his father's fork into his plate. The Rebbe Rashab smiled and remarked: “He's not yet agreeable…”
When does the food desire that a man should eat it? — Only when he eats it not for the sake of his own desire but for the sake of the food's desire; i.e., he eats in order to elevate the food. If, however, he eats because of his own desire — i.e., he eats the food for his own need, since he wants to be a recipient and derive his nourishment from it — then not only does he not elevate the food, but in fact the food downgrades his spiritual standing. This in turn downgrades the standing of the food itself, because through it the man stumbled .
Along similar lines, my revered father-in-law, the Rebbe [Rayatz], once stated in a sichah : While walking down the street one should think about words of Torah. (The subject matter varies from person to person — Chassidus, Gemara, Mishnayos, Ein Yaakov, or at least  a verse of Chumash or Tehillim.) If he does not think about words of Torah, the cobblestone on which he steps cries out to him: “Clod! Who are you to tread on me?”
It is true that the man is more elevated than the stone — a medaber, an articulate human, as against a domem, an inanimate object. However, the medaber is superior only when his conduct is directed by his intellective soul . But when a spirit of folly  enters him, so that he does not fulfill his function as a thinking being and is therefore called a clod, then the cobblestone protests: “Clod! Who are you to tread on me?”
Nevertheless, even after all these reasoned explanations have been made, the mortal mind (including the mind of a Jew) is still bothered by a question: Granted that what the Torah forbids is forbidden — but when it comes to things that are permitted according to the Torah and the Shulchan Aruch, why should a person be told that these too should not be done?
In response to this question: One should not debate it by means of human logic, because here one will find a kashe (a logical query) based on a statement in the Talmud Bavli, and there one will find a kashe based on a statement in the Talmud Yerushalmi, and so on and so forth. Rather, the approach that is called for is kabbalas ol, an unquestioning acceptance of the yoke of heaven, and mesirus nefesh, self-sacrifice. What is required in the early stages of one’s avodah is kabbalas ol; at a higher level this becomes mesirus nefesh — for, as Chassidus explains, mesirus nefesh (lit., “surrendering one’s soul”) basically means mesiras haratzon (“surrendering one's will”), because nefesh [also] means “will”. This surrender of one's will also includes one's will in matters of kedushah (which is a Jew’s real will, as Rambam states as a psak din in the course of a halachic decision ). Such a surrender of the will obligates one to leap out of all his inhibiting restraints, including those involving kedushah.
This approach is especially required in the time of galus (now that  “because of our sins we were exiled from our Land”) — because at a time like this, avodah that follows the dictates of reason and commonsense will not suffice. What is needed is mesirus nefesh, for this is what gives Jews the stamina to survive the trek through galus. (Tanya explains why “Moshe Rabbeinu… commanded… to the generation that entered the Land that they recite the Shema twice daily in order to acknowledge the Sovereignty of Heaven with self-sacrifice” — but this explanation speaks only of potential self-sacrifice, whereas the era of exile requires actual self-sacrifice.) One of the proofs for this is the fact that it is specifically during the era of exile that self-sacrifice is present and manifest.
To revert to Avraham Avinu: We can now appreciate why, when he began his period of exile, G-d commanded him to “go forth from your land”, to step beyond his accustomed limits . This would empower him to go “to the land”, to go out to the world. He knew that though  “travel lessens three things”, not only would nothing be weakened with relation to himself, but, moreover , “I shall make your name great” — i.e., Your Name, the Divine Name Havayah, the Name of G-d's Essence (as is expounded in Chassidus ). Moreover, Avraham Avinu’s self-transcendence would empower him to attain the level of the circumcision — the revelation of sublime spiritual lights, a revelation that resembles birth .
Read more in the sicha.