I was recently cast as the lead in my school's musical. I normally sing bass 2 but will be singing up and beyond my range for this show. The problem I always seem to have is that my voice deteriorates extremely quickly. I sing in so many other groups at my school besides our musical, and I will not be dropping any of those any time soon. Some of my friends seem to have an "iron voice." No matter what they do, how loud they scream, how sick they are etc., they NEVER lose their voices. I on the other hand baby my voice. I drink so much water in a day, use a humidifier, drink hot tea, and warm up like none other, yet I always am the first person to lose my voice. I've talked to my director about it and he has no solid answer for me. I am really scared for this musical as it is a long one and I want to do well but also have very little vocal endurance. How can I fix this? Does anybody know any vocal exercises to increase my vocal endurance? How do I "develop" an Iron Voice?