Why isn't this size improver script not working when the value is over 20?

When size is more then 20 its supposed to print("Over 20") why isn't it working? When it is over 20 it doesnt do anything instead the value of size keeps going.Test it and you will see

player = script.Parent.Parent
char = player.Character
mouse = player:GetMouse()
hold = false
function keydown(key)
    key = key:lower()
    if key == "z" then
        hold = true
        bricksize()
    end
end


function bricksize()
    size = 0
    if size > 20 then
        hold = false
        print("OVer 20")
    end
    while hold == true do
    wait()
    size = size+1
    print(size)
    end
end


function keyup(key)
    key = key:lower()
    if key == "z" then
        hold = false
    end
end


if hold == false then
    size = 0
end
mouse.KeyDown:connect(keydown)
mouse.KeyUp:connect(keyup)