How to make a stamina system to work with my sprint and input system?

[Scryllix]

I want to make a stamina system for a horror survival game i am making where the player can sprint for around 5 seconds before the stamina running out and having to wait for around 3 seconds before being able to sprint again. Only issue is, I’m fairly new to unity and C# and so am not 100% sure on how to do this for it to work in my game. Any help or pointers would be great.
Below are the two other code files that I have written which cover the movement and the player sprinting.

Main Movement

using System;
using System.Diagnostics.Contracts;
using UnityEngine;
using UnityEngine.InputSystem;

public class Player : MonoBehaviour
{
    [SerializeField] float mouseSensitivity = 3f;
    [SerializeField] float movementSpeed = 5f;
    [SerializeField] float mass = 1f;
    [SerializeField] float acceleration = 20f;
    public Transform cameraTransform;

    public float Height
    {
        get => controller.height;
        set => controller.height = value;
    }

    public event Action OnBeforeMove;

    internal float movementSpeedMultiplier;

    CharacterController controller;
    internal Vector3 velocity;
    Vector2 look;

    PlayerInput playerInput;
    InputAction moveAction;
    InputAction lookAction;
    InputAction sprintAction;

    void Awake()
    {
        controller = GetComponent<CharacterController>();
        playerInput = GetComponent<PlayerInput>();
        moveAction = playerInput.actions["move"];
        lookAction = playerInput.actions["look"];
        sprintAction = playerInput.actions["sprint"];
    }
    void Start()
    {
        Cursor.lockState = CursorLockMode.Locked;
    }

    // Update is called once per frame
    void Update()
    {
        UpdateGravity();
        UpdateMovement();
        UpdateLook();
    }
    
    void UpdateGravity()
    {
        var gravity = Physics.gravity * mass * Time.deltaTime;
        //determines the vertical velocity
        velocity.y = controller.isGrounded ? -1f : velocity.y + gravity.y;
    }

    Vector3 GetMovementInput()
    {
        //takes horizontal and vertical input from the keyboard
        //var x = Input.GetAxis("Horizontal");
        var y = Input.GetAxis("Vertical");

        var moveInput = moveAction.ReadValue<Vector2>();

        var input = new Vector3();
        //input vector by adding the vector pointing from the player forwards, multiplied by 'y'
        //'w' and 's' keys
        input += transform.forward * moveInput.y;
        //input vector by adding the vector pointing from the player, to the right, multiplied by 'x'
        //'a' and 'd' keys
        input += transform.right * moveInput.x;
        //prevents the player from moving faster when moving diagonally 
        input = Vector3.ClampMagnitude(input, 1f);
        input *= movementSpeed * movementSpeedMultiplier;
        return input;
    }
    void UpdateMovement()
    {
        movementSpeedMultiplier = 1f;
        OnBeforeMove?.Invoke();

        var input = GetMovementInput();

        var factor = acceleration * Time.deltaTime;
        velocity.x = Mathf.Lerp(velocity.x, input.x, factor);
        velocity.z = Mathf.Lerp(velocity.z, input.z, factor);
        

        controller.Move(velocity * Time.deltaTime);
    }
    void UpdateLook()
    {
        var lookInput = lookAction.ReadValue<Vector2>();
        look.x += lookInput.x * mouseSensitivity;
        look.y += lookInput.y * mouseSensitivity;

        look.y = Mathf.Clamp(look.y, -89f, 89f);

        //rotates the player object
        transform.localRotation = Quaternion.Euler(0,look.x, 0);
        //cannot do the same for the 'y' rotation as we need to angle the player object itself
        cameraTransform.localRotation = Quaternion.Euler(-look.y, 0, 0);
        
    }
}

Sprinting System

using System;
using UnityEngine;
using UnityEngine.InputSystem;

[RequireComponent(typeof(Player))]
public class PlayerSprinting : MonoBehaviour
{
    //will show up in Unity to allow me to easily edit it
    [SerializeField] float speedMultiplier = 2f;

    Player player;
    PlayerInput playerInput;
    InputAction sprintAction;

    void Awake()
    {
        //calls component from 'player' file
        player = GetComponent<Player>();
        //calls component from 'playerInput' file in unity which is naming each input
        playerInput = GetComponent<PlayerInput>();
        //is calling the new method we made in Unity called sprint
        sprintAction = playerInput.actions["sprint"];
    }

    void OnEnable() => player.OnBeforeMove += OnBeforeMove;
    void OnDisable() => player.OnBeforeMove += OnBeforeMove;

    void OnBeforeMove()
    {
        var sprintInput = sprintAction.ReadValue<float>();
        if (sprintInput == 0) return;
        //combines the players forward vector with the velocity for sprint
        //Clamp01 only takes the forward input meaning the player can only sprint when moving forwards
        var forwardMovementFactor = Mathf.Clamp01(
            Vector3.Dot(player.transform.forward, player.velocity.normalized)
            );
        var multiplier = Mathf.Lerp(1f, speedMultiplier, forwardMovementFactor);
        player.movementSpeedMultiplier *= multiplier;
    }
}