Staying mellow while conducting

Whenever choral directors conducted any of the orchestras in which I played, I noticed that they never seemed very temperamental.  Unlike orchestra conductors, I don't recall any choir director getting all that upset with an orchestra.  Most likely, it's because they were used to working with singers.  When you get angry with your choir, you risk making the singers' voices tense up, which could result in them sounding strained and tentative.  I'd like to think that a calm, cool approach is best, generally, when conducting any orchestra or chorus.  It's good to see a conductor's mellow demeanor reap rewards.