Rav  Shalom Noach Berezovsky zt’l, the Slonimer Rebbe

In is series of seforim, Nesivos Shalom, the Slonimer Rebbe zt’l writes (in one of the many sections on Tikun HaMiddos):

One needs to feel the joy of acquiring positive traits and realize how miserable he is as long as he is mired in negativity. A person of positive traits is happy—at peace with others, at peace with God, at peace with himself. The opposite is true of one whose traits are negative—he is irritable, not at peace with others, God, or himself. It is contention within your gates—within your own personal gates there is contention: He fumes with anger at himself; he is depressed and lethargic; he is full of jealousy and animosity toward others; he doesn’t like to be around people and they don’t like to be around him; he is full of bitterness at the Almighty concerning his lot. Once a person comes to the clear realization that his happiness actually depends on the rectification of his character, he will spare no effort in pursuit of his own happiness. The whole of a person’s life and times hinges on his character. (Translation by R Jonathan Glass)