This is for singers. Most people when they are in a hurry doing a concert, or singing in church, OR practice for that fact, don't warm up, and just dive right into it. That's stupid. I'm sorry, but I am a firm advocate of warming up, and before I sing, you can find me in the back of the hall at least 30 minutes before, warming up. But you don't have to warm up as much as I do, but please warm up some. Do some simple exercises, sing up a scale note by note, do something. If you don't warm up, you could seriously mess up your vocal cords. I cannot tell you how many people I have seen who went to go sing without doing warm ups, and ending up scarring their vocal cords from the strain. You HAVE to exercise your cords before you do anything more strenuous than softly singing. This is especially true for opera singers. If you want to be at your best at all times, and have your voice survive your many solos and concerts, then please warm up.