Shalom,
I have started a RAMBAM class held by my Rabbi and we are currently studying Hilchot De'os of Mishne Torah. Here Rambam teaches us that a Jew (or any pious individual) must walk the 'middle road' and not be extreme in any character trait. Indeed many JTF members could learn a whole lot by studying these laws. Many here are too extreme and may even be violating these laws.
http://www.chabad.org/library/article_cdo/aid/910340/jewish/Deot-Chapter-One.htm
Halacha 1Each and every man possesses many character traits. Each trait is very different and distant from the others.
One type of man is wrathful; he is constantly angry. [In contrast,] there is the calm individual who is never moved to anger, or, if at all, he will be slightly angry, [perhaps once] during a period of several years.
There is the prideful man and the one who is exceptionally humble. There is the man ruled by his appetites - he will never be satisfied from pursuing his desires, and [conversely,] the very pure of heart, who does not desire even the little that the body needs.
There is the greedy man, who cannot be satisfied with all the money in the world, as [Ecclesiastes 5:9] states: "A lover of money never has his fill of money." [In contrast,] there is the man who puts a check on himself; he is satisfied with even a little, which is not enough for his needs, and he does not bother to pursue and attain what he lacks.
There is [the miser,] who torments himself with hunger, gathering [his possessions] close to himself. Whenever he spends a penny of his own, he does so with great pain. [Conversely,] there is [the spendthrift,] who consciously wastes his entire fortune.
All other traits follow the same pattern [of contrast]. For example: the overly elated and the depressed; the stingy and the freehanded; the cruel and the softhearted; the coward and the rash. and the like.
Halacha 2Between each trait and the [contrasting] trait at the other extreme, there are intermediate points, each distant from the other.
With regard to all the traits: a man has some from the beginning of his conception, in accordance with his bodily nature. Some are appropriate to a person's nature and will [therefore] be acquired more easily than other traits. Some traits he does not have from birth. He may have learned them from others, or turned to them on his own. This may have come as a result of his own thoughts, or because he heard that this was a proper trait for him, which he ought to attain. [Therefore,] he accustomed himself to it until it became a part of himself.
Halacha 3The two extremes of each trait, which are at a distance from one another, do not reflect a proper path. It is not fitting that a man should behave in accordance with these extremes or teach them to himself.
If he finds that his nature leans towards one of the extremes or adapts itself easily to it, or, if he has learned one of the extremes and acts accordingly, he should bring himself back to what is proper and walk in the path of the good [men]. This is the straight path.
Halacha 4The straight path: This [involves discovering] the midpoint temperament of each and every trait that man possesses [within his personality.] This refers to the trait which is equidistant from either of the extremes, without being close to either of them.
Therefore, the early Sages instructed a man to evaluate his traits, to calculate them and to direct them along the middle path, so that he will be sound {of body}.
For example: he should not be wrathful, easily angered; nor be like the dead, without feeling, rather he should [adopt] an intermediate course; i.e., he should display anger only when the matter is serious enough to warrant it, in order to prevent the matter from recurring. Similarly, he should not desire anything other than that which the body needs and cannot exist without, as [Proverbs 13:25] states: "The righteous man eats to satisfy his soul."
Also, he shall not labor in his business except to gain what he needs for immediate use, as [Psalms 37:16] states: "A little is good for the righteous man."
He should not be overly stingy nor spread his money about, but he should give charity according to his capacity and lend to the needy as is fitting. He should not be overly elated and laugh [excessively], nor be sad and depressed in spirit. Rather, he should be quietly happy at all times, with a friendly countenance. The same applies with regard to his other traits.
This path is the path of the wise. Every man whose traits are intermediate and equally balanced can be called a "wise man."
Halacha 5A person who carefully [examines] his [behavior], and therefore deviates slightly from the mean to either side is called pious.
What is implied? One who shuns pride and turns to the other extreme and carries himself lowly is called pious. This is the quality of piety. However, if he separates himself [from pride] only to the extent that he reaches the mean and displays humility, he is called wise. This is the quality of wisdom. The same applies with regard to other character traits.
The pious of the early generations would bend their temperaments from the intermediate path towards [either of] the two extremes. For some traits they would veer towards the final extreme, for others, towards the first extreme. This is referred to as [behavior] beyond the measure of the law.
We are commanded to walk in these intermediate paths - and they are good and straight paths - as [Deuteronomy 28:9] states: "And you shall walk in His ways."
Halacha 6[Our Sages] taught [the following] explanation of this mitzvah:
Just as He is called "Gracious," you shall be gracious;
Just as He is called "Merciful," you shall be merciful;
Just as He is called "Holy," you shall be holy;
In a similar manner, the prophets called God by other titles: "Slow to anger," "Abundant in kindness," "Righteous," "Just," "Perfect," "Almighty," "Powerful," and the like. [They did so] to inform us that these are good and just paths. A person is obligated to accustom himself to these paths and [to try to] resemble Him to the extent of his ability.
Halacha 7How can one train himself to follow these temperaments to the extent that they become a permanent fixture of his [personality]?
He should perform - repeat - and perform a third time - the acts which conform to the standards of the middle road temperaments. He should do this constantly, until these acts are easy for him and do not present any difficulty. Then, these temperaments will become a fixed part of his personality.
Since the Creator is called by these terms and they make up the middle path which we are obligated to follow, this path is called "the path of God." This is [the heritage] which our Patriarch Abraham taught his descendants, as [Genesis 18:19] states: "for I have known Him so that he will command his descendants...to keep the path of God."
One who follows this path brings benefit and blessing to himself, as [the above verse continues]: "so that God will bring about for Abraham all that He promised."