turning off keys?[NOT ANSWERED]

wait(0.01)
local enabled = true
Player = game.Players.LocalPlayer
character = Player.Character
mouse = Player:GetMouse()
run = game:GetService("RunService")
Humanoid = Player.Character.Humanoid
Nen = Player.Nen

function Charging(key)
    key = key:lower()
    if key == "0" then
        while wait(0.1) do
            if Nen.Value < 100 then
                Nen.Value = Nen.Value +1
                wait()
            else if Nen.Value >= 100 then
                Nen.Value = Nen.Value +0
                end
            end
        end
    end
end

mouse.KeyDown:connect(Charging)

How do i make it to were if i let go if left shift it stops charging?