How do you disable your character from jumping?

I know that it can be done, but I am not sure how. I also tried bodyforce, but that doesn't work. Any suggestions?

Here's my attempt

local mouse = game.Players.LocalPlayer:GetMouse()

mouse.KeyDown:connect(function(key)
    if key:lower() == "SpaceBar" then
        humanoid.Jump = false
    end
end)