Game stopping at Pause?

Hello, I was wondering how I could get the player to stop moving and the game to stop when the pause menu is opened (via esc) then resumed after the esc key is pressed.

Yes I have looked through google and I've looked for hours...

 void Start()
 {
     this.currentMenuComponent = MainMenuComponent;
 }

 void Update()
 {
     if (Input.GetKeyDown (KeyCode.Escape))

     {
         if (showGUI == false)
         {
             showGUI = true;
             return;
         }

         if (showGUI == true)
         {
             showGUI = false;
             this.currentMenuComponent = MainMenuComponent;
             return;
         }
     }
 }