[ANSWERED] How to make BodyVelocity only change 1 axis velocity?

The question says it all. How would I make BodyVelocity only change 1 axis? The BodyVelocity is in the players head and I am trying to make the player go up at a constant rate when they press SPACE without affecting their WASD movement (x and z-axis) but, when in mid-air, their WASD movement gets suspended and they travel up only. How can I make it so that body velocity only affects their y-axis?

I tried this:

local bodyvelocity = Instance.new("BodyVelocity")
bodyvelocity.Parent = character.Head
bodyvelocity.P = 1000

mouse.KeyDown:connect(function (key)
    key = string.lower(key)
    if string.byte(key) == 32 then
        spacedown = true
        bodyvelocity.Velocity = Vector3.new(0,1,0)
    end
end)

This is in a Local Script in the player. 'character' and 'mouse' are defined. The script works but when flying up, the player can no longer use WASD to move their x and z-axis. How would I make the BodyVelocity only affect the y-axis and still allow WASD movement?