Condition on Character Movement

I copied and pasted the character movement script from one of the Unity sample projects. The code is below. How do I make it so this movement only occurs when the player is holding down a key/button?

Thank you.

 using UnityEngine;

 public class Char1MovementAlt : MonoBehaviour
 {
 public float speed = 6f;            // The speed that the player will move at.
 
 Vector3 movement;                   // The vector to store the direction of the player's movement.
 Animator anim;                      // Reference to the animator component.
 Rigidbody playerRigidbody;          // Reference to the player's rigidbody.
 int floorMask;                      // A layer mask so that a ray can be cast just at gameobjects on the floor layer.
 float camRayLength = 100f;          // The length of the ray from the camera into the scene.
 
 void Awake ()
 {
     // Create a layer mask for the floor layer.
     floorMask = LayerMask.GetMask ("Floor");
     
     // Set up references.
     anim = GetComponent <Animator> ();
     playerRigidbody = GetComponent <Rigidbody> ();
 }
 
 
 void FixedUpdate ()
 {
     // Store the input axes.
     float h = Input.GetAxisRaw ("Horizontal");
     float v = Input.GetAxisRaw ("Vertical");
     
     // Move the player around the scene.
     Move (h, v);
 }
 
 void Move (float h, float v)
 {
     // Set the movement vector based on the axis input.
     movement.Set (h, 0f, v);
     
     // Normalise the movement vector and make it proportional to the speed per second.
     movement = movement.normalized * speed * Time.deltaTime;
     
     // Move the player to it's current position plus the movement.
     playerRigidbody.MovePosition (transform.position + movement);
 }
 }