Help with "if" function.

Questions & Answers
1

Right now I am working on a stamina bar for the player, where whenever he presses space the slider decreases, and whenever he lets go it increases. But the problem is I don’t want it to increase immediately after, instead wait 5 seconds for example. I tried using “yield new WaitForSeconds(5);” but that didn’t work as the statement is a void and has to be Coroutine. Does anyone have any idea how I can do this thanks!
using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;

public class Stamina : MonoBehaviour
{
    [Range(0, 25)] public float stamina = 25;
    float maxStamina;
    public Slider staminaBar;
    public float dValue;


    void Start()
    {
        maxStamina = stamina;
        staminaBar.maxValue = maxStamina;
    }

    // Update is called once per frame
    void Update()
    {
        if (Input.GetKey(KeyCode.LeftShift) && Input.GetKey(KeyCode.W) || Input.GetKey(KeyCode.LeftControl)) 
        { 
            DecreaseEnergy();
        }
        
        else if (stamina != maxStamina)
        {
            IncreaseEnergy();
        }

        staminaBar.value = stamina;
    }

    private void DecreaseEnergy()
    {
        if(stamina>=0) 
            stamina -= dValue*Time.deltaTime;
        
    }

    private void IncreaseEnergy()
    {    
        if (stamina<=25)
        stamina += dValue*Time.deltaTime;   
    }

}
2

I would just make a timer:

// variables
public float refillDelay = 5;
float refillTimer;

In Update function:

      if (Input.GetKey(KeyCode.LeftShift) && Input.GetKey(KeyCode.W) || Input.GetKey(KeyCode.LeftControl)) 
     { 
         DecreaseEnergy();
         refillTimer = refillDelay;
     }
         
     else if (stamina != maxStamina & refillTimer <= 0)
     {
         IncreaseEnergy();
     }
     refillTimer -= Time.deltaTime;