How to make character run using the new input system?

I'm trying to add a running feature to my character controller movement. I want the character to run when the Z key is being held. I'm using the new input system and here is my attempt:

     Vector3 horizontalVelocity;
     [SerializeField] CharacterController controller;
     [SerializeField] float walkSpeed = 10f;
     [SerializeField] float runSpeed = 25f;
     bool running; 
     private void Update()
        {
    if (running)
            {
                moveSpeed = runSpeed;
                horizontalVelocity = (transform.right * horizontalInput.x + transform.forward * horizontalInput.y) * moveSpeed;
                controller.Move(horizontalVelocity * Time.deltaTime);
            }
            else
            {
                moveSpeed = walkSpeed;
                horizontalVelocity = (transform.right * horizontalInput.x + transform.forward * horizontalInput.y) * moveSpeed;
                controller.Move(horizontalVelocity * Time.deltaTime);
            }
}
     public void OnRunning() {
            running = true;
        }

And I handled the Input Action in another class like so:

  [SerializeField] Movement movement;
 PlayerControls controls; 
    PlayerControls.GroundMovementActions groundMovement;
 private void Awake() 
  {
 groundMovement.Running.performed += _ => movement.OnRunning();
}
  private void OnEnable()
    {
        controls.Enable(); 
    }

    private void OnDestroy()
    {
        controls.Disable(); 
    }

it is not working, whether I press the z or not it is just walking normally. Does not run when I hold the z key.