How to make the players jumppower lower or higher depending on his speed?

What im trying to make is a script that disables jumping when your character is walking slow (<13) and jump high when your character is running (>13)

local Character = game.Players.LocalPlayer.Character or game.Players.LocalPlayer.CharacterAdded:Wait()

local Humanoid = Character:WaitForChild("Humanoid") 
local jump = game.StarterPlayer.CharacterJumpPower 

jump = 1

local lowspeed = 13
local highspeed = 20

Humanoid.Running:Connect(function(speed2)
    if speed2 < lowspeed then jump = 0
    else if speed2 > lowspeed and speed2 < highspeed then jump = 39.643
        else if speed2 > highspeed then jump = 42

            end
        end

    end
end)