I was talking to my friend yesterday and he mentioned, that he is grappling with understanding, regulating, discerning and tweaking emotions.

This in fact is the purpose of our existence.

One of the greatest Jewish Rabbis/saints (author of Chovois Halivavois) in the introduction, writes, that after the great saints and scholars of the Talmud had mastered the Torah, the rest of their life was dedicated to tweaking their emotions.

Generally, the great and holy Rambam, writes, as Jewish law (besides for anger and arrogance, which must be completely avoided) the correct path is the middle of the road, however those who are punctilious, will, punctiliously (that means carefully (as if their soul survival depends on it) see each and every emotion:

(Now obviously awareness – for without knowing an emotion – hardly can you change or stop one, so please see my Booklet on Self Awareness )

Now everything God made (including anger and arrogance) has a purpose (as our sages said, “Everything God made, was made for His glory” (…something positive – the trick is, of-course discernment:)

Emotion Good Bad
Love Unconditional (unconditional love, means that you see the other as yourself! – as the Baal Shem Tov says, that the Mitzvah “to love your fellow as yourself,” is to think about that which causes you to love them – for once this feeling is implemented in your heart, the rest can/will follow.  

Practically, realize a. they are a fellow Jew b. Your souls come from one source. c. See what’s special in them
Lust As the Alter Rebbe writes, lust within the context of marriage, for the right purpose, is good All other: pornography, imagery, in fact, even looking at a woman (and the many other Jewish laws..) lustfully, is bad.
Brains Aristotle said, the greatest pleasure is intellectualism; so while using your head for good and necessary things is good… …Using your brain as a means of intellectual entertainment (I recall when I taught in University, I realized this is merely an “intellectual disneyland”) is bad.
Desire Obviously desire is a primary motive (if not THE!)   So it is obvious that to desire, that which God wishes of you, is great! In fact all desires – are a form of Avodah-Zara, which is a “foreign service” (effectively, as it is our strongest of our multiple desires, that wins – hence for a person to have inner peace, their final desire, must be to do the will of God, which can be ascertained through Torah/Mitzvos; and having a Mashpia. See the first page of Kabbalah-Love (available for free, on my website)
Hate Hate is so bad that it’s the cardinal sin – the cause of all sins (of-course, the antidote is forgiveness, hence one must believe that all comes from a loving God; as well as try to see the good in the bad, and then the bad feels good.) The only exception to bad hate is, the commandment to hate Amalek (for “compassion to cruelty is to be cruel to the compassionate” – not to mention, if fear is your motive, than you will become what you fear, unless you hate it.)