The Voice is a unique instrument. It is different for different people. For a vocalist, the voice is their primary instrument. So if anyone asks, ‘What do you play?’, You answer saying, ‘I sing, I am a singer!’. The voice is different from other instruments. Why do I say that?
Unlike a guitar or a piano, the voice is an actual part of you. So it feels everything that you feel. If you are tired, your voice is also tired. If you are excited, so is your voice. So just like how the human body has limitations, the voice also does. This is what makes it different from other instruments. You can practice on a guitar for 2 hours and the guitar as such wont feel tired. But the voice does since it is not an object like a guitar. So apart from being an instrument, it is also a physical part of you. So it is up to us to take good care of your physical and mental health to keep your voice in check and in tune.