Bereishis, 32:30: “Then Yaakov asked, and he said, ‘please tell me your name’. And he said, ‘Why then do you inquire of my name’? And he blessed him there.”
Rashi, 32:30, Dh: “We do not have a fixed name, our names change according to the current mission that we are sent on.”
After Yaakov was successful in his seminal battle with the Malach, the Malach asked Yaakov his name, and when Yaakov answered, the angel told him that his name would now be known as Yisrael. Yaakov then asked the Malach for his name, but the Malach refused to answer, and instead asked, why Yaakov was asking him his name. Rashi explains that the Malach was saying that Malachim have no set name, rather their names are dependent upon the current mission that they have been sent on. There are two basic questions on this episode. Firstly, why was Yaakov asking the Malach for his name? Secondly, we do in fact know the name of this Malach: Chazal tell us that Hewas the Guardian Angel of Esav, which is also known as the Satan and which represents the yetser hara. If so, why, according to Rashi, did he say that his name changes according to his mission?
When Yaakov asked the Malach for his name, he wasn’t simply trying to ascertain a way to identify the Malach. Rather, we know that that the name of something defines it’s essence. When Yaakov asked the Malach his name, he was asking what was his essence? In this way, he was hoping to gain a deeper understanding of the nature of the Satan and the challenges it would pose to his descendants. When the Malach replied by telling him that it does not help to know his essence, because there is no one aspect of the yetser hara that he would have to conquer. Rather, he was saying that his essence is that he adapts to the times and circumstances to pose the exact spiritual challenge that the Jewish people as a whole, and each Jew as an individual, will face throughout the generations. Sometimes he would come in the form of false ideologies such as Hellenism or Communism, at other times, he will come in the form of challenges such as technological advances.
On a more individual level, the Gemara in Chullin alludes to two different ways that the yetser hara works. The Gemara brings a Machlokes as to the appearance of the Malach. One opinion holds that he appeared to Yaakov like an idol worshipper, and the other holds that he appeared in the guise of a Talmid Chacham. Rav Yissachar Frand, shlit’a explains that the yetser hara can be both; there is no one definition and no one battle plan. Yet it needs to be understood on a deeper level, what these two manifestations represent. The idol worshipper aspect of the yetser hara is not too difficult to comprehend. He encourages us to weaken in our avodas HaShem by preventing us from doing Mitzvos, but what does the Talmid chacham aspect of the yetser hara do?
Rav Frand answers based on the tefillah we say in Maariv: “May you remove the Satan from before us and from behind us”. “Before us” refers to how the Satan stands in front of us to block us from doing Mitzvos. “Behind us” refers to how, on occasion, the Satan deems it necessary to stand behind us and actually pushes us to do Mitzvos. What does that mean? It means that there are times when a person undergoes a significant, positive transformation and takes on new aspects of Torah observance. This is obviously a great thing, and the yetser hara is unable to prevent him from progressing, but it does not just stand idly by and let the person continue unimpeded. Rather, it tries to make the person change too fast or take on too much in one go, instead of following the sensible approach of piecemeal growth. Indeed, it is not uncommon for baalei teshuva to face the yetser hara of moving too fast and then at some point, feeling overburdened by their new commitments.
The yetser hara makes a particular effort to prevent a Jew from Torah learning as that is the basis of our whole avodas HaShem. For some, it suffices to distract them in various ways, but it can also utilize the aspect of being “behind us” by pushing a person to overexert themselves in their learning to the extent that they burn out or become ill from not getting enough rest. There were Gedolim who, at a young age, experienced this phenomenon to the extent that they needed a significant period of recuperation where they could not learn on the same level. After this experience, they exhort their students to be careful to not push themselves too far.
We have learnt that there is no single approach of the yetser hara, rather it adapts to the times and circumstances, and according to each individual. It is incumbent on each person to zero in on the particular areas where his yetser hara is strongest.
 The basis of this answer was heard from Rav Yissachar Frand shlit’a, in the name of Rav Chaim Dov Heller, shlit’a.
 Chullin, 91a.
 Needless to say, that the more relevant aspect of the yetser hara with regard to learning, is to reduce our learning, not to make us do too much.