I have recently taken up singing and it is a wonderful way to relax. One of the benefits of learning how to sing is that you must learn how to breathe properly. The deep breathing that is done in singing is also the same kind of breathing you might use for yoga or other types of deep breathwork.
Some also believe that sounds can be healing and that by singing we can bring more health to our bodies. In the least, you can help make your soul happier.
I recently had a friend mention that she was using sound therapy to work out some of her longstanding issues with depression and anxiety, and she reports that it's really been working wonders. Her sound therapy includes singing but it also includes making spontaneous sounds that range from guttural to lilting, depending on how she feels. It sounds exhilarating, kind of like giving a voice to a repressed emotion. I'm sometimes a little self-conscious when it comes to singing, but I agree with you--it's something that makes me feel vibrant, carefree, and happy when I do it, so perhaps I should just go with it a lot more.
Singing is an amazing activity. Not only is it beneficial for the person singing but it can bring happiness to those around them as well. Babies and children love to be sung to; it helps them to feel happy and fall asleep. The rhythm of your voice will lull you or your listener into a happier state. Also, having grown up as a member or choirs and choral camp, I agree that yoga breath comes from the same place singing breath does-the diaphragm. I was glad to learn that my years of practice in "singing from the belly" came in handy when I started doing yoga. By linking singing and yoga together here, you've mixed two of my favourite activities.