Singing is more than a fun activity—there are documented physical and psychological benefits!
strengthen the immune system
reduce heart rate and blood pressure
increase lung capacity
tone diaphragm, abdominal and intercostal muscles
help build concentration, memory, and listening skills
build self-esteem and confidence
act as an anti-depressant
"Wired for Sound: Oliver Sacks, MD, the noted neurologist and author, describes the profound bond between music and our brains and how the simple act of singing can be good medicine—especially as we age." ...read full article.
"Studies have linked singing with a lower heart rate, decreased blood pressure, and reduced stress, according to Patricia Preston-Roberts, a board-certified music therapist in New York City." ...read full article.
"...research published in the Journal of Music Therapy in 2004 suggested that group singing helped people to cope better with chronic pain." ...read full article.
"The medical profession strongly believes that singing is a good form of aerobic exercise for the abdominal muscles, the lungs and the circulation of blood." ...read full article.
For further reading (or rather, listening):
Check out these podcasts from The Library of Congress: Music and the Brain. "The Library's Music and the Brain events offer lectures, conversations and symposia about the explosion of new research at the intersection of cognitive neuroscience and music."