Singing may be something that people say is hard to break into or hard to make a living doing, but most people don't realize all of the potential outlets for singers and other musicians. I sing for several different ensembles and own my own singing telegram business. Private teaching and coaching can also be lucrative. One of my ensembles travels keeping me out of town about 20 weekends a year singing at festivals and universities. Form a small specialized ensemble and sell it. Churches hire singers and choir directors. Professional choirs exist... and if you can't find one you like, direct your own! Non-professional choirs everywhere hire directors and coaches. Offer your voice for weddings.
If you are going to sing for a living, you must not be shy, but you must not be too big for your britches. You must know your strengths and not be afraid to sell them. If you are a fragile singer (my voice is tired, I can't sing too much in rehearsal or I'll have nothing for the concert, I'm sick) either fix it or don't bother. No one wants to work with someone they can't depend on. You should be able to sing no matter how sick you are. Only if you are in the hospital, do you have a valid excuse.
Don't be afraid to go ten different directions. Some things don't pay very much, but when you add all the bits up, you just might make a living and be happy! Understand that I will never be rich or make it big. I'm not interested in that. I want to sing and grow and learn in my specific genre, and I love knowing that I have the freedom to do that.