The very last pasuk in this week's parsha reads: "You shall observe the words of this covenant 'lman taskilo' (lit. so that you will succeed) in all that you do." Rav Wolbe (Alei Shur vol. I pg. 89) cites the translation of the Targum Yerushalmi which differs from the simple interpretation of the pasuk: "You shall guard the words of this Torah and observe them so that you will contemplate all that you do." Accordingly, the purpose of the entire Torah is to transform the impetuous impulsive person into a misbonein - one who contemplates and analyzes all that he does.
Hisboninus is the key which unlocks the spiritual treasure chest. How does one achieve perfection in the performance of mitzvos? How does one acquire emunah and bitachon? How can one perform proper teshuvah? They can all be attained through the trait of hisboninus. This, in essence, is the purpose of mussar study; to aid us in being misbonein into ourselves and our relationship with the Torah and mitzvos.
One who studies the classic mussar sefer, Mesillas Yesharim, will perceive that hisboninus is the key to acquiring each of the middos discussed in his ladder toward character perfection. The very first middah discussed is Zehirus - vigilance, and besides it itself being a form of hisboninus, it is also acquired, "through hisboninus regarding the enormity of our avodah." Nekius is attained "through constant study of Chazal's words," Prishus through a penetrating gaze into the negative aspects of worldly pleasures, and Tahara is achieved by, "One (who) delves and constantly thinks about the lowliness of this world." Chassidus can be reached "when one is misbonein deeply about Hashem's great loftiness," Anava through "habitually being misbonein where one came from" and Yiras Cheit through "being misbonein into the fact that there is a Shechina and He knows all that occurs."
It could very well be, continues Rav Wolbe, that many people find mussar study difficult simply because they never acquired this trait of hisboninus. This being the case, there is no better time to work on attaining this trait than the weeks before Rosh Hashana. Take one single mussar thought and try to be misbonein into it (e.g. "One who gets angry is as if he has worshipped an idol.") Think about it, ponder its meaning, contemplate its truth and then see how your actions correspond to your newfound knowledge. The results of this exercise might be astounding!