Access a variable from another script in update function

I have a script that constantly checks if a bool is true or false, and a second script that does something. Now I want the second script to only do something when the bool is returned true. So on runtime I want script2 to constantly check if the bool in script1 is true, so something like this.

if(bool == true)

what is the most efficient, most elegant way to do this? Thank you very much!

I would do it this way.
In Script1 I would create an event like this:

public event EventHandler<object,EventArgs> SomethingHappened;

and when something happens, i.e. your bool value is set I’d fire this event

if (SomethingHappened != null) SomethingHappened(this, EventArgs.Empty);

In Script2 I would have a field referencing Script1 to subscribe to this event:

public Script1 MyScript;

void OnEnable()
  if (MyScript) MyScript.SomethingHappened += onSomethingHappened;

void OnDisable()
  if (MyScript) MyScript.SomethingHappened -= onSomethingHappened;

void onSomethingHappened(object sender, EventArgs e)
  // do something

And set MyScript in inspector.
This way you don’t need loops, nor Script1 knows what other scripts are interested in something happening inside.