How to add sprinting and crouching?

Hello everyone, I am creating a sandbox game and I need my character to be able to sprint and crouch. This is my c# script:

private Rigidbody player;
private bool canJump = true;
private RaycastHit ray;

public float walkSpeed;
public float gravity;

void Start() {
	Cursor.lockState = CursorLockMode.Locked;
	player = GetComponent<Rigidbody> ();
}

void FixedUpdate() {
	Physics.Raycast (transform.position, Vector3.down, out ray);
	if(Vector3.Distance(transform.position,ray.point) < 1.1) {
		canJump = true;
	}
	if (Input.GetKey(KeyCode.Space)) {
		if (canJump == true) {
			player.velocity = Vector3.up * gravity;
			canJump = false;
		}
	}
	if (Input.GetKey (KeyCode.W)) {
		transform.Translate (Vector3.forward * walkSpeed);
	}
	if (Input.GetKey (KeyCode.A)) {
		transform.Translate (Vector3.left * walkSpeed);
	}
	if (Input.GetKey (KeyCode.S)) {
		transform.Translate (Vector3.back * walkSpeed);
	}
	if (Input.GetKey (KeyCode.D)) {
		transform.Translate (Vector3.right * walkSpeed);
	}
}

Thanks in advance.

Never mind, I answered it. Here’s the code just in case there were others in the same boat:

private Rigidbody player;
private bool canJump = true;
private RaycastHit ray;
private float speed;

public float walkSpeed;
public float gravity;
public float sprintSpeed;

void Start() {
	Cursor.lockState = CursorLockMode.Locked;
	player = GetComponent<Rigidbody> ();
}

void FixedUpdate() {
	Physics.Raycast (transform.position, Vector3.down, out ray);
	speed = walkSpeed;

	if(Vector3.Distance(transform.position,ray.point) < 1.1) {
		canJump = true;
	}
	if (Input.GetKey(KeyCode.Space)) {
		if (canJump == true) {
			player.velocity = Vector3.up * gravity;
			canJump = false;
		}
	}
	if (Input.GetKey(KeyCode.LeftShift)) {
		speed = sprintSpeed;
	}
	if (Input.GetKey (KeyCode.W)) {
		transform.Translate (Vector3.forward * speed);
	}
	if (Input.GetKey (KeyCode.A)) {
		transform.Translate (Vector3.left * speed);
	}
	if (Input.GetKey (KeyCode.S)) {
		transform.Translate (Vector3.back * speed);
	}
	if (Input.GetKey (KeyCode.D)) {
		transform.Translate (Vector3.right * speed);
	}
}