Roblox Script Generated by ScripterAI

"make a shift to spring with little bar on the bottom of the screen for cooldown, make it so the sprint is on cooldown, and is hold, not toggle."

```lua
-- local script (StarterGUI) 
local player = game.Players.LocalPlayer
local character = player.Character or player.CharacterAdded:Wait()
local humanoid = character:WaitForChild("Humanoid")
local screenGui = Instance.new("ScreenGui", player.PlayerGui)

local sprintBar = Instance.new("Frame", screenGui)
sprintBar.BackgroundColor3 = Color3.fromRGB(0, 255, 0)
sprintBar.AnchorPoint = Vector2.new(0.5, 1)
sprintBar.Position = UDim2.new(0.5, 0, 1, -10)
sprintBar.Size = UDim2.new(0.3, 0, 0.02, 0)

local sprintBarFill = Instance.new("Frame", sprintBar)
sprintBarFill.BackgroundColor3 = Color3.fromRGB(255, 255, 255)
sprintBarFill.Size = UDim2.new(1, 0, 1, 0)

local sprintCooldown = 5
local sprintDuration = 2
local sprintSpeed = 2 * humanoid.WalkSpeed
local normalSpeed = humanoid.WalkSpeed
local isSprinting = false
local canSprint = true

local function updateSprintBarFill()
    sprintBarFill.Size = UDim2.new(canSprint and 1 or 0, 0, 1, 0)
end

local function startSprint()
    if canSprint then
        isSprinting = true
        humanoid.WalkSpeed = sprintSpeed

canSprint = false
        updateSprintBarFill()

wait(sprintDuration)

isSprinting = false
        humanoid.WalkSpeed = normalSpeed

wait(sprintCooldown)

canSprint = true
        updateSprintBarFill()
    end
end

local function onInputBegan(input, gameProcessed)
    if input.KeyCode == Enum.KeyCode.LeftShift and not gameProcessed then
        if not isSprinting then
            startSprint()
        end
    end
end

player:GetMouse().KeyDown:Connect(onInputBegan)
```
This script creates a sprint bar at the bottom of the screen, and allows the player to sprint by holding the left shift key. The sprint has a cooldown and duration, and the player's speed increases while sprinting.