Singing is good for you, physically, emotionally, psychologically, spiritually and socially.
A good breathing technique is required for singing; it also has other benefits. Taking in the correct amount of oxygen to the body helps to release muscle tension, and breathing correctly helps your body burn more calories. (How to lose weight without over-exertion!).
Research has shown that singing has the physical effect of releasing pleasure-inducing endorphins; respiration and blood circulation.
Singing helps to express feelings and emotions. It can also enhance spiritual and religious thought and activity.
Singing in groups (choirs, choruses, chorales, etc) means singing - and socialising - with other people. Harmony, solidarity and unity are not only buzz words for aspiring political leaders: they are the bed-rock of ensemble-singing.
"Since singing is so good a thing I wish all men would learne to sing"
1 First, it is a knowledge safely taught and quickly learned, where there is a good Master, and an apt Scholler.
2 The exercise of singing is delightfull to Nature, & good to preserve the health of Man.
3 It doth strengthen all parts of the brest, & doth open the pipes.
4 It is a singular good remedie for a stutting and stamering in the speech.
5 It is the best means to procure a perfect pronounciation, & to make a good Orator.
6 It is the onely way to know where Nature hath bestowed the benefit of a good voyce : which guift is so rare, as there is not one among a thousand, that hath it.
7 There is not any Musicke of Instruments whatsoever, comparable to that which is made of the voyces of Men, where the voyces are good, and the same well sorted and ordered.
8 The better the voyce is, the meeter it is to honour and serve God there-with : and the voyce of man is chiefely to bee imployed to that ende.
And if you think that Byrd lived too long ago to be relevant in the 21st century, have a look at some of the more recent evidence that singing is good for you:
Sing for Your Heart More information about the health benefits, physical and psychological, can be found at: http://www.singforyourheart.org.uk/
Good vibrations: Take a deep breath and let it all out... Wendy Moore sings her way to a stress-free life. This article was published in The Observer newspapaer in 2001. (Nikki Slade, mentioned in the article, is no relation to Charles Slade) http://www.guardian.co.uk/theobserver/2001/feb/11/life1.lifemagazine6
Singing can help lift depression, according to researchers at Western Ontario University, Canada. And closer to home . . . a choir is proving to be a canny cure for people with asthma and other serious breathing problems. http://www.thesun.co.uk/sol/homepage/woman/health/article575611.ece
"Since singing is so good a thing I wish all men would learne to sing" 
Sing for Your Heart More information about the health benefits, physical and psychological, can be found at: 
Singing, particularly in a chorus, seems to benefit the elderly particularly well. As part of a three-year study examining how singing affects the health of those 55 and older, a Senior Singers Chorale was formed by the Levine School of Music in Washington, D.C. For more details, go to: 
Singing can help lift depression, according to researchers at Western Ontario University, Canada. And closer to home . . . a choir is proving to be a canny cure for people with asthma and other serious breathing problems. 
And using your diaphragm, as all singers are encouraged to do, is a good way to promote a healthy lymphatic system, according to Dr Ben Kim: