Stamina script system

Hi, I'm trying to make a stamina system for a FPS controller I'm making but it wont work. Unity says the variable running and StartReloadingStamina exists but isnt in use, which doesnt make sense. This breaks the running system and pretty much allows you to run forever. Thanks to whoever can fix it for me :)

P.S: If you could put comments within the code to show me where I made the error, I would be greatful.

 {
     public float speed = 6.0F;
     public float jumpSpeed = 8.0F;
     public float gravity = 20.0F;
     bool running;
     bool StartReloadingStamina = true;
     private const float _waitTime = 5;
     private Vector3 moveDirection = Vector3.zero;
     float stamina = 5;
     ///Variables within script
     IEnumerator Cooldown()
     {
         StartReloadingStamina = false;
         // wait for set amount of time
         yield return new WaitForSeconds(_waitTime);
         StartReloadingStamina = true;
     }
     ///Above is Stamina Cooldown
     ///
 
     void Update()
     {
 
         {
             CharacterController controller = GetComponent<CharacterController>();
             if (controller.isGrounded)
             {
                 moveDirection = new Vector3(Input.GetAxis("Horizontal"), 0, Input.GetAxis("Vertical"));
                 moveDirection = transform.TransformDirection(moveDirection);
                 moveDirection *= speed;
                 if (Input.GetButton("Jump"))
                 {
                     moveDirection.y = jumpSpeed;
                 }
                 if (Input.GetKeyDown(KeyCode.LeftShift))
                 {
                     if (stamina > 0)
                     {
                         running = true;
                         speed = 8.0F;
                         stamina -= Time.deltaTime;
 
                         if (stamina < 0)
                         {
                             speed = 6.0F;
                             running = false;
                             StartCoroutine(Cooldown());
                         }
                     }
                 }
                     ///GKU is when key is released
                     if (Input.GetKeyUp(KeyCode.LeftShift))
                     {
                         running = false;
                         StartCoroutine(Cooldown());
                         speed = 6.0F;
                     }
                 }
 
                 moveDirection.y -= gravity * Time.deltaTime;
                 controller.Move(moveDirection * Time.deltaTime);
                 ///Uses character controller for physics. 
 
             }
         }
     }