Life RPG Movement

using UnityEngine;
using System.Collections;

public class PlayerController : MonoBehaviour
{
    //Variables
    public float speed = 5.0F;
    public float jumpSpeed = 8.0F;
    public float gravity = 20.0F;
    private Vector3 moveDirection = Vector3.zero;
    bool hasSkateboard = true;

    void Update()
    {
        CharacterController controller = GetComponent<CharacterController>();
        // is the controller on the ground?
        if (controller.isGrounded)
        {
            //Feed moveDirection with input.
            moveDirection = new Vector3(Input.GetAxis("Horizontal"), 0, Input.GetAxis("Vertical"));

            //Prevents player from moving twice as fast by holding two keys.
            if (moveDirection.sqrMagnitude > 1.0f)
            {
                moveDirection.Normalize();
            }

            moveDirection = transform.TransformDirection(moveDirection);
            //Multiply it by speed.
            moveDirection *= speed;
            //Jumping
            if (Input.GetButton("Jump"))
                moveDirection.y = jumpSpeed;

            //Is shift held down, and does the player have a skateboard? If so, increase speed (Using skateboard)
            if (hasSkateboard == true && Input.GetKey(KeyCode.LeftShift))
            {
                speed = 10.0F;
            }

        }

        else
        {   //If the player has fallen off the platform, return them to the platform.
            if (transform.position.y < -7)
            {
                transform.position = new Vector3(0, 2.7f, 0);
            }
        }

        //If escape is pressed, quit the game.
        if (Input.GetKeyDown(KeyCode.Escape))
        {
            Application.Quit();
        }



        //No skateboard? Fine, walking speed then (5.0f, not extremely slow, but infuriating)
        else
        {
            speed = 5.0F;
        }


        //Applying gravity to the controller
        moveDirection.y -= gravity * Time.deltaTime;

        //Making the character move
        controller.Move(moveDirection * Time.deltaTime);
    }
}