A dehydrated and tired voice is an environment conducive to vocal damage. Eliminate every potentially harmful factor that is in your control.
2. Keep Talking to a Minimum.
Don't overwork your voice. Don't talk loud. Don't yell. If your vocal cords aren't swollen already, they are more susceptible to swelling when you're tired.
If you believe that singing is your calling, then have faith that God wants to help you succeed and carry you through your bad days.