You can damage your vocal cords! Check out this singer's techniques in how to properly exercise and elasticize your money makers.
I said to her, "What floor?," as one does in New York — you're going to push the button for someone. And with those two words, she said, "Oh, you've got a serious voice injury." And I said, "Oh, it's nothing. It'll clear up." And she said, "No, no, no. I work with Broadway singers."