Unity - Shift to sprint - unity3d

Question

friends, new dev asking, I looked through a lot of sites and tried a lot of different scripts separate scripts from player movement and other scripts to no avail and came up with this as a conglomeration of what I've seen but it also doesn't work, at all. I couldn't find anything in subreddits or this. I know my normal movement code is probably ugly but it works. I hope you can help thank you!
TO clarify this is making the player sprint while holding down the shift key thank you for those who reminded me to elaborate.
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
[RequireComponent(typeof(UnityEngine.AI.NavMeshAgent))]
public class PlayerMovement : MonoBehaviour
{
UnityEngine.AI.NavMeshAgent agent;
private Rigidbody rb;
public float movementSpeed = 5.0f;
public float clockwise = 1000.0f;
public float counterClockwise = -5.0f;
public float Speed = 5.0f;
public Vector3 jump;
public float jumpForce =1.0f;
public float shiftSpeed = 10.0f;
public bool isGrounded;
void Start()
{
rb = GetComponent<Rigidbody>();
jump = new Vector3(0.0f, 1.0f, 0.0f);
agent = GetComponent<UnityEngine.AI.NavMeshAgent>();
}
void OnCollisionStay()
{
isGrounded = true;
}
void Update()
{
if (Input.GetKey(KeyCode.W) || Input.GetKey(KeyCode.UpArrow))
{
transform.position += transform.forward \* Time.deltaTime \* movementSpeed;
}
else if (Input.GetKey(KeyCode.W) || Input.GetKey(KeyCode.UpArrow) && Input.GetKey(KeyCode.LeftShift))
{
transform.position += transform.forward \* Time.deltaTime \* shiftSpeed;
}
else if (Input.GetKey(KeyCode.S) || Input.GetKey(KeyCode.DownArrow))
{
transform.position -= transform.forward \* Time.deltaTime \* movementSpeed;
}
else if (Input.GetKey(KeyCode.S) || Input.GetKey(KeyCode.DownArrow) && Input.GetKey(KeyCode.LeftShift))
{
transform.position += transform.forward \* Time.deltaTime \* shiftSpeed;
}
else if (Input.GetKey(KeyCode.A) || Input.GetKey(KeyCode.LeftArrow))
{
GetComponent<Rigidbody>().position += Vector3.left \* Time.deltaTime \* movementSpeed;
}
else if (Input.GetKey(KeyCode.A) || Input.GetKey(KeyCode.LeftArrow) && Input.GetKey(KeyCode.LeftShift))
{
transform.position += transform.forward \* Time.deltaTime \* shiftSpeed;
}
else if (Input.GetKey(KeyCode.D) || Input.GetKey(KeyCode.RightArrow))
{
GetComponent<Rigidbody>().position += Vector3.right \* Time.deltaTime \* movementSpeed;
}
else if (Input.GetKey(KeyCode.D) || Input.GetKey(KeyCode.RightArrow) && Input.GetKey(KeyCode.LeftShift))
{
transform.position += transform.forward \* Time.deltaTime \* shiftSpeed;
}
if (Input.GetKeyDown(KeyCode.Space) && isGrounded)
{
rb.AddForce(jump \* jumpForce, ForceMode.Impulse);
isGrounded = false;
}
}
}

Answer 1

I assume what you are asking is "How to make my player move faster when I hold down the shift key?"
I would suggest having two constants for walking speed and running speed. Then another variable that changes based on if the shift key is held:
private const float walkSpeed = 5.0f;
private const float runSpeed = 10.0f;
private float moveSpeed = walkSpeed; // Our current movement speed
//...
void Update() {
//...
if (Input.GetKey(KeyCode.LeftShift) {
// Set current speed to run if shift is down
moveSpeed = runSpeed;
}
else {
// Otherwise set current speed to walking speed
moveSpeed = walkSpeed;
}
}