Trying to make it so a player has an interval between uses of the health boosting ability?

It all works besides line 67 which I can't figure out what I need to put there so that a player can not just use the healing ability without any limitations.

Here's the script:

THANK YOU SO MUCH IN ADVANCE!

-- SETTINGS
local offset = Vector3.new(40, 80, 0)

local plr = game.Players.LocalPlayer

local sg = game:GetService("StarterGui")	

sg:SetCore("TopbarEnabled", false)

local mouse = plr:GetMouse()

local hmnd = plr.Character:FindFirstChild("Humanoid")

hmnd.MaxHealth = script.MAXHP.Value

hmnd.JumpPower = 0

hmnd.AutoRotate = false

local cam = game.Workspace.CurrentCamera 

local fov = 70
	
local speedval = 18.5

local runService = game:GetService("RunService")

sg:SetCore("TopbarEnabled", false)
cam.FieldOfView = fov
mouse.Icon = "http://www.roblox.com/asset/?id=611298909"
hmnd.WalkSpeed = speedval

local function onRenderStep()
	local pos = plr.Character.Torso.Position --Adds the position values of the player's position and the previously set offset
	local campos = pos + offset	
	cam.CoordinateFrame = CFrame.new(campos, pos) --Sets the camera's position to have an X value of the player's position and the Y value of camPos which is the player position plus the set offset
	plr.Character.Torso.CFrame = CFrame.new(plr.Character.Torso.Position,Vector3.new(mouse.Hit.p.X, plr.Character.Torso.Position.Y, mouse.Hit.p.Z))
end
	
runService:BindToRenderStep('Camera', Enum.RenderPriority.Camera.Value, onRenderStep)
	
-- USER INPUT 

-- ABILITIES

uis = game:GetService("UserInputService")

local canBeUsed = false

function hpRegen(inputObject, gameProcessedEvent)
	if inputObject.KeyCode == Enum.KeyCode.Q and hmnd.Health < hmnd.MaxHealth and canBeUsed == true then
		canBeUsed = true
		local hp = hmnd.Health 
		local increase = script.HPBOOST.Value
		hmnd.Health = math.min(hmnd.Health + increase, hmnd.MaxHealth)
		local hpfxone = game.ServerStorage.hpgaineffect:Clone()
		hpfxone.Parent = plr.Character.Torso
		local hpfxtwo = game.ServerStorage.hpgaineffect:Clone()
		hpfxtwo.Parent = plr.Character.Torso
		local fire = game.ServerStorage.hpfire:Clone()
		fire.Parent = plr.Character.Torso
		wait(1.45)
		hpfxone:Destroy()
		hpfxtwo:Destroy()
		fire:Destroy()
	
-- PUT STUFF HERE

	end
	end



	

	
	function speedUpgrade(inputObject, gameProcessedEvent, placetime, timewaited)
if inputObject.KeyCode == Enum.KeyCode.LeftShift and canBeUsed== true then
	canBeUsed = true
	cam.FieldOfView = 85
	while hmnd.WalkSpeed > 18.5 do
		wait(0.5)
	hmnd.WalkSpeed = hmnd.WalkSpeed - 1.25
	
	if hmnd.WalkSpeed == 17.5 then
		wait(0.1) 
		canBeUsed = true
		
		
		
		
end
end
end
end
	


	
	function speedUpgradeEnd()
		hmnd.WalkSpeed = script.DEFAULTSPEED.Value
		cam.FieldOfView = 70
	end


uis.InputBegan:connect(hpRegen)
uis.InputBegan:connect(speedUpgrade)
uis.InputEnded:connect(speedUpgradeEnd)

Use a bool. Maybe put a bool value in the script. For example

if script.bool = true then
--code
end