Reducing an int "while" a bool is true

Greetings community! I am a new to Unity as of March. Here is the breakdown of my question, my object has a script attached, with a int value for mood. I want the mood to be reduced by 10 while the bool “exhausted” == true. I feel I would need this check in update but…
If I put this in the update frame as so:

void Update()
    {
    if (exhausted ==true)
                  {
                         mood -=10; 
                  }
    }

the problem of course is that this will reduce mood by 10 every frame while exhausted is true.
Any advice much appreciated!

I don’t wanna look smarty but let me correct. This language is C#, unity dosen’t use C++.

About the problem the solution is simple, just set your exhausted to false again:

void Update()
     {
     if (exhausted ==true)
                   {
                          mood -=10; 
                          exhausted = false;
                   }
     }

Hope that helps.