To modify your existing script so that the player's walk speed and jump power are only activated while the Shift key is pressed, you'll want to incorporate input handling using the `UserInputService`. Here's an updated version of your script that implements this functionality:
```lua
local UserInputService = game:GetService("UserInputService")
local walkSpeed = 40 -- Change this number to your preferred speed
local jumpPower = 50
-- Access


