The end does not justify the means.

A person should not determine his course of action solely for the purpose of the accomplishment. A person is obligated to do that which is demanded of him, and it is for Hashem to bring results. It is incumbent upon man to act, not to accomplish.

Yosef's brothers justified their cruelty to him by their belief that he was a vainglorious dreamer. This was the cause of their ability to justify their actions. We have to be sure that every action we take is correct, regardless of the anticipated result.

from the Sefer "Reb Chaim's Discourses" The shmussen of the Mirrer Rosh Yeshiva Rabbi Chaim Shmulevitz ztl page 99

Woe to Us on the Day of Rebuke

The Midrash tells us that Yosef's brothers were overwhelmed by his rebuke, yet the Pasuk says that all that he said was, "Ani Yosef- I am Yosef".  Where is the rebuke that the Midrash refers to? 

This teaches us that rebuke is not verbal castigation that we have come to see it as, rather it is making a person aware of the the fact that he has erred.  When a person realizes that he has lived his life with a totally mistaken perspective, then rebuke has accomplished its purpose.

from the Sefer "Reb Chaim's Discourses" THe shmussen of the Mirrer Rosh Yeshiva Rabbi Chaim Shmulevitz ztl  page 98

A tool for fighting the Yetzer Hara

From a Shiur by Shira Smiles-Parshat Vayigash: Dual Flames

The Yetzer Hara works by making us feel removed from Hashem. We can fight this by saying, "Hashem is here now!"