How do I have a button repeat an action for as long as I have the button depressed?

Friends,

I tried the following, but it never stopped the process when I released the mouse button:

    Private Sub btnFaster_Hold(ByVal sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles btnFaster.MouseDown
        While Control.MouseButtons() = Windows.Forms.MouseButtons.Left
            If tbSpeedThreshold.Value < 20 Then
                tbSpeedThreshold.Value += 1

                System.Threading.Thread.Sleep(500)
                If Control.MouseButtons. = Windows.Forms.MouseButtons.None Then
                    SetSpeedThreshold()
                    Exit Sub
                End If
            End If
        End While
    End Sub