Aside from being a singer, there a lot of other jobs that requires your voice –  recruitment officer doing interviews for 8 hours day, 5 days a week. A call center agent talking to customers with different personalities from different parts of the world non-stop because they have a service level they need to reach. A teacher teaching classes everyday or your mom scolding you for not doing your daily chores.  It is inevitable that your own career could take its toll on your voice, like when you get sore throat.