Script becoming too big to maintain?

So I've got a script on the player that handles basically everything that has to do with the player, but I'm not really sure what to do when the script gets this big, it's getting too big to handle and I'm not sure what to do if it were to grow to like 1,000 lines at some point. Should I be breaking this up even though it all seems to have something to do with the player?

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.UI;
 using UnityStandardAssets.Characters.FirstPerson;
 using UnityEngine.EventSystems;
 
 public class PlayerScript : DavidBehaviour{
 
     public List<RaycastResult> Results = new List<RaycastResult>();
 
     public string[] Recipes;
     public GameObject[] Objects;
 
     public GameObject SelectedItem;
     public GameObject TargetedBlock;
     public GameObject SelectionBar;
     public GameObject TheCamera;
 
     public GameObject CraftingGrid;
     public GameObject Inventory;
     public GameObject OutputSlot;
     public GameObject Menu;
 
     public GameObject MouseSlot;
 
     public GameObject[] HotSlots;
     public GameObject[] InventorySlots;
     public GameObject[] AllSlots;
 
     public GameObject[] CraftingGridSlots;
 
     public float MoveSpeed;
     public float WalkProgress;
 
     public int SelectedSlotNumber;
 
     public bool InventoryFull;
     public bool Grounded;
     public bool MenuShown;
 
     public Texture2D MouseTexture;
 
     void Start () {
         //Cursor.SetCursor (MouseTexture, Vector3.zero, CursorMode.Auto);
         Cursor.lockState = CursorLockMode.Locked;
     }
 
     void Update ()
     {
         if (MouseSlot.GetComponent<SlotScript> ().ContainedItem != null) {
             MouseSlot.SetActive (true);
             MouseSlot.transform.position = Input.mousePosition;
         } else {
             MouseSlot.SetActive (false);
         }
 
         if (AllSlots [SelectedSlotNumber]) {
             SelectedItem = (AllSlots [SelectedSlotNumber]);
         } else {
             SelectedItem = null;
         }
 
         if (Input.GetKeyDown ("e")) {
             if (MenuShown) {
                 MenuShown = false;
                 Menu.SetActive (false);
                 Cursor.visible = false;
                 Cursor.lockState = CursorLockMode.Locked;
             } else {
                 MenuShown = true;
                 Menu.SetActive (true);
                 Cursor.visible = true;
                 Cursor.lockState = CursorLockMode.None;
             }
         }
 
         if (MenuShown == true) {
             GetComponent<CameraMouseLook> ().CanMove = false;
         } else {
             GetComponent<CameraMouseLook> ().CanMove = true;
         }
 
         if (!MenuShown) {
             if (Input.GetMouseButtonDown (1)) {
                 if (SelectedItem != null){
                     if (SelectedItem.GetComponent<SlotScript>().ContainedItem.GetComponent<ItemScript>().BlockForm != null){
                         var Block = SelectedItem.GetComponent<SlotScript>().ContainedItem.GetComponent<ItemScript> ().BlockForm;
                         Ray TheRay = new Ray (Camera.main.transform.position, Camera.main.transform.forward);
                         RaycastHit HitResult;
                         if (Physics.Raycast (TheRay, out HitResult, 5)) {
                             if (Vector3.Distance (HitResult.transform.gameObject.transform.position + HitResult.normal, transform.position) >= 1) {
                                 var PlacedBlock = Instantiate (Block, HitResult.transform.gameObject.transform.position + HitResult.normal, Quaternion.identity);
                                 PlacedBlock.name = SelectedItem.name;
                                 PlaySound ("PlaceBlock", PlacedBlock.transform.position, (3 + Random.value) / 3.5f, 2);
                                 ChangeItemAmount (SelectedItem.GetComponent<SlotScript>().ContainedItem, -1);
                             }
                         }
                     }
                 }
             }
 
             if (Input.GetKeyDown ("q")) {
                 if (HotSlots [SelectedSlotNumber].GetComponent<SlotScript>().ContainedItem != null) {
                     var DroppedItem = Instantiate (HotSlots [SelectedSlotNumber].GetComponent<SlotScript>().ContainedItem, Camera.main.transform.position + Camera.main.transform.forward, Quaternion.identity);
                     DroppedItem.GetComponent<ItemScript> ().ItemAmount = 1;
                     DroppedItem.SetActive (true);
                     DroppedItem.name = HotSlots [SelectedSlotNumber].GetComponent<SlotScript>().ContainedItem.name;
                     DroppedItem.GetComponent<Rigidbody> ().AddForce (Camera.main.transform.forward * 200);
                     if (HotSlots [SelectedSlotNumber].GetComponent<SlotScript>().ContainedItem.GetComponent<ItemScript> ().ItemAmount > 1) {
                         HotSlots [SelectedSlotNumber].GetComponent<SlotScript>().ContainedItem.GetComponent<ItemScript> ().ItemAmount += -1;
                     } else {
                         Destroy (HotSlots [SelectedSlotNumber].GetComponent<SlotScript>().ContainedItem);
                         HotSlots [SelectedSlotNumber].GetComponent<SlotScript>().ContainedItem = null;
                     }
                 }
             }
 
             if (Input.GetMouseButton (0)) {
                 Ray TheRay = new Ray (Camera.main.transform.position, Camera.main.transform.forward);
                 RaycastHit HitResult;
                 if (Physics.Raycast (TheRay, out HitResult, 100)) {
                     if (HitResult.transform.gameObject.GetComponent<BlockScript> () != null) {
                         TargetedBlock = HitResult.transform.gameObject;
                         TargetedBlock.GetComponent<BlockScript> ().Brokeness += Time.deltaTime / HitResult.transform.gameObject.GetComponent<BlockScript> ().Hardness;
                         if (TargetedBlock.GetComponent<BlockScript> ().Brokeness >= 1) {
                             TargetedBlock.GetComponent<BlockScript> ().Break ();
                         }
                     }
                 }
             } else if (TargetedBlock != null) {
                 TargetedBlock.GetComponent<BlockScript> ().Brokeness = 0;
                 TargetedBlock = null;
             }
         } else {
 
             CraftObject ();
 
             if (Input.GetMouseButtonDown (0)) {
                 var Pointer = new PointerEventData (EventSystem.current);
                 Pointer.position = Input.mousePosition;
                 EventSystem.current.RaycastAll (Pointer, Results);
                 if (Results.Count > 0) {
                     var ClickedItem = Results [0].gameObject;
                     if (ClickedItem.GetComponent<SlotScript> () != null) {
                         MoveItemToNewSlot (ClickedItem, MouseSlot);
                     }
                 }
             } else if (Input.GetMouseButtonDown (1)) {
                 var Pointer = new PointerEventData (EventSystem.current);
                 Pointer.position = Input.mousePosition;
                 EventSystem.current.RaycastAll (Pointer, Results);
                 if (Results.Count > 0) {
                     var ClickedItem = Results [0].gameObject;
                     if (ClickedItem.GetComponent<SlotScript> () != null) {
                         MoveOneItemToNewSlot (ClickedItem, MouseSlot);
                     }
                 }
             }
         }
 
         if (Input.GetAxis ("Mouse ScrollWheel") > 0) {
             SelectedSlotNumber += 1;
             if (SelectedSlotNumber > 9) {
                 SelectedSlotNumber = 0;
             }
             SelectionBar.transform.position = HotSlots [SelectedSlotNumber].transform.position;
         }
         if (Input.GetAxis ("Mouse ScrollWheel") < 0) {
             SelectedSlotNumber += -1;
             if (SelectedSlotNumber < 0) {
                 SelectedSlotNumber = 9;
             }
             SelectionBar.transform.position = HotSlots [SelectedSlotNumber].transform.position;
         }
 
         Ray FloorRay = new Ray (transform.position + new Vector3 (0, -1.1f, 0), -transform.up);
         RaycastHit FloorHit;
         if (Physics.Raycast (FloorRay, out FloorHit, 0.5f)) {
             if (FloorHit.transform.gameObject != null) {
                 Grounded = true;
             } else {
                 Grounded = false;
             }
         }
 
         if (Input.GetKeyDown (KeyCode.Space) & Grounded == true) {
             GetComponent<Rigidbody> ().AddForce (transform.up * 15000);
             Grounded = false;
         }
     }
 
     void FixedUpdate(){
         if (Input.GetKey ("w")) {
             transform.position = Vector3.Lerp (transform.position, transform.position + transform.forward, Time.deltaTime * MoveSpeed);
             if (Grounded == true){
                 WalkProgress += 0.05f;
                 if (WalkProgress >= 1) {
                     PlaySound ("Footstep" + Random.Range (1, 4), transform.position, 1, 2);
                     WalkProgress = 0;
                 }
             }
         }
         if (Input.GetKey ("s")) {
             transform.position = Vector3.Lerp (transform.position, transform.position + transform.forward * -0.5f, Time.deltaTime * MoveSpeed);
             if (Grounded == true) {
                 WalkProgress += 0.025f;
                 if (WalkProgress >= 1) {
                     PlaySound ("Footstep" + Random.Range (1, 4), transform.position, 1, 2);
                     WalkProgress = 0;
                 }
             }
         }
         if (Input.GetKey ("d")) {
             transform.position = Vector3.Lerp (transform.position, transform.position + transform.right, Time.deltaTime * MoveSpeed);
         }
         if (Input.GetKey ("a")) {
             transform.position = Vector3.Lerp (transform.position, transform.position + transform.right * -1, Time.deltaTime * MoveSpeed);
         }
     }
 
     void OnCollisionEnter(Collision TheCollision){
         if (TheCollision.gameObject.GetComponent<ItemScript> () != null) {
             var InventoryNumber = 0;
             var SlotFound = false;
             var EmptySlots = new List<GameObject> ();
             foreach (GameObject Slot in AllSlots) {
                 if (Slot.GetComponent<SlotScript> ().ContainedItem != null) {
                     if (Slot.GetComponent<SlotScript> ().ContainedItem.name == TheCollision.gameObject.name) {
                         ChangeItemAmount (Slot.GetComponent<SlotScript> ().ContainedItem, TheCollision.gameObject.GetComponent<ItemScript> ().ItemAmount);
                         Destroy (TheCollision.gameObject);
                         PlaySound ("Pop", transform.position, 1, 3);
                         SlotFound = true;
                         break;
                     }
                 } else {
                     EmptySlots.Add (Slot);
                 }
             }
             if (SlotFound == false) {
                 if (EmptySlots.Count > 0) {
                     EmptySlots [0].GetComponent<SlotScript> ().ContainedItem = TheCollision.gameObject;
                     TheCollision.gameObject.SetActive (false);
                     PlaySound ("Pop", transform.position, 1, 3);
                 } else {
                     InventoryFull = true;
                 }
             }
         }
     }
             
 
     void ChangeItemAmount(GameObject Item, int Difference){
         Item.GetComponent<ItemScript> ().ItemAmount += Difference;
         if (Item.GetComponent<ItemScript> ().ItemAmount < 1) {
             Destroy (Item);
         }
     }
 
     void CraftObject(){
         var i = 0;
         var CraftingString = "";
         foreach (GameObject Slot in CraftingGridSlots) {
             if (CraftingGridSlots [i].GetComponent<SlotScript> ().ContainedItem != null) {
                 CraftingString += CraftingGridSlots [i].GetComponent<SlotScript> ().ContainedItem.GetComponent<ItemScript> ().name;
             } else {
                 CraftingString += "Empty";
             }
             i += 1;
         }
         foreach (GameObject Object in Objects) {
             if (CraftingString == Object.GetComponent<ItemScript> ().CraftingRecipe) {
                 if (OutputSlot.GetComponent<SlotScript> ().ContainedItem == null) {
                     var CraftedItem = Instantiate (Object, Camera.main.transform.position + Camera.main.transform.forward, Quaternion.identity);
                     CraftedItem.GetComponent<ItemScript> ().ItemAmount = 1;
                     CraftedItem.name = Object.name;
                     CraftedItem.SetActive (false);
                     OutputSlot.GetComponent<SlotScript> ().ContainedItem = CraftedItem;
                 }
             } else {
                 if (OutputSlot.GetComponent<SlotScript> ().ContainedItem != null) {
                     OutputSlot.GetComponent<SlotScript> ().ContainedItem = null;
                 }
                 Debug.Log (CraftingString);
                 Debug.Log(Object.GetComponent<ItemScript> ().CraftingRecipe);
             }
         }
     }
 
     public void WipeGrid(){
         var i = 0;
         foreach (GameObject Slot in CraftingGridSlots){
             if (Slot.GetComponent<SlotScript> ().ContainedItem != null) {
                 ChangeItemAmount (Slot.GetComponent<SlotScript>().ContainedItem, -1);
             }
             i += 1;
         }
     }
 
     public void MoveItemToNewSlot(GameObject OriginalSlot, GameObject NewSlot){
         if (MouseSlot.GetComponent<SlotScript> ().ContainedItem == null) {
             if (OriginalSlot == OutputSlot) {
                 WipeGrid();
             }
         }
         if (NewSlot.GetComponent<SlotScript> ().ContainedItem == null) {
             NewSlot.GetComponent<SlotScript> ().ContainedItem = OriginalSlot.GetComponent<SlotScript> ().ContainedItem;
             OriginalSlot.GetComponent<SlotScript> ().ContainedItem = null;
         } else {
             if (OriginalSlot.GetComponent<SlotScript>().ContainedItem != null){
                 if (OriginalSlot.GetComponent<SlotScript> ().ContainedItem.name == NewSlot.GetComponent<SlotScript> ().ContainedItem.name) {
                     NewSlot.GetComponent<SlotScript> ().ContainedItem.GetComponent<ItemScript> ().ItemAmount += OriginalSlot.GetComponent<SlotScript> ().ContainedItem.GetComponent<ItemScript> ().ItemAmount;
                     Destroy (OriginalSlot.GetComponent<SlotScript> ().ContainedItem);
                 }
             }
             var OldItem = NewSlot.GetComponent<SlotScript> ().ContainedItem;
             NewSlot.GetComponent<SlotScript> ().ContainedItem = OriginalSlot.GetComponent<SlotScript> ().ContainedItem;
             OriginalSlot.GetComponent<SlotScript> ().ContainedItem = OldItem;
         }
     }
     public void MoveOneItemToNewSlot(GameObject OriginalSlot, GameObject NewSlot){
         if (NewSlot.GetComponent<SlotScript> ().ContainedItem == null) {
             if (OriginalSlot.GetComponent<SlotScript> ().ContainedItem != null){
                 if (OriginalSlot.GetComponent<SlotScript> ().ContainedItem.GetComponent<ItemScript> ().ItemAmount > 1) {
                     var NewItem = Instantiate (OriginalSlot.GetComponent<SlotScript> ().ContainedItem, Vector3.zero, Quaternion.identity);
                     NewItem.GetComponent<ItemScript> ().ItemAmount = 1;
                     NewItem.name = OriginalSlot.GetComponent<SlotScript> ().ContainedItem.name;
                     OriginalSlot.GetComponent<SlotScript> ().ContainedItem.GetComponent<ItemScript> ().ItemAmount += -1;
                     NewSlot.GetComponent<SlotScript> ().ContainedItem = NewItem;
                 }
             }
         }
     }
 }