One of the four major branches of emotional intelligence (according to John D. Mayer and Peter Salovey) is the ability to reflectively regulate or manage emotions. This applies to managing your own emotions rather than those of other people. According to research by this team, people who understand their own emotions and “are confident about their abilities to regulate their affect, seem to be able to repair their moods more quickly and effectively following failure.” 
There are two things about this finding that piqued by interest. As regulating one’s own emotions and repairing one’s own mood are basically the same ability, these two skills should definitely be found in the same people. However, people only “seem” to do this. The person who manages their own emotions may appear to minimize disappointment, frustration and anger while being disturbed as the person who frets, sulks and rants after their plans bite the dust. However, the first group is definitely more pleasant to be around. If you are naturally reserved and never exhibit much emotion, you may have been told to be more open, because people cannot read you. However, if some people are experts are manipulating their own affect, others are not really reading them either.
People who are able to mold their own emotions to create favorable impressions of themselves must work at this. You do not remain calm and collected when others panic if you don’t put effort into learning this skill. Controlling emotional expressiveness come at a price, and one of the costs seems to be less expertise in skills that require logic. Psychologists Dana Joseph (University of Central Florida) and Daniel Newman (University of Illinois) analyzed every study they could find on the connection between job performance and emotional intelligence. Interestingly, certain types of jobs are performed better by people who don’t read others emotions and regulate their own. In these positions, such as mechanic, scientist or accountant, people with higher emotional intelligence typically exhibited poorer performance.
While it is a good idea to learn how to hide exhibits of anger. It is not necessarily a bad thing to show a lack of enthusiasm or empathy. In learning the emotional expressiveness that enables you to persuade others, you may be sacrificing just as important skills that are part of very necessary professions.
 Salovey, Mayer, Goldman, Turvey, & Palfai, 1993 (http://www.unh.edu/emotional_intelligence/EI%20Assets/Reprints…Mood%20Meas%20and%20Mood%20Cong/CA1995SaloveyMayer.pdf)