Ok... but I can't get that close to my horse with a whip.
And yes all I use is a halter.. but I don't really have the money to invest in a cavesson... so I'm not sure what I should do.
Then don't use a whip. I've found that a lunge whip can be too much for certain horses. With my mare I just use a dressage whip that I leave on the ground unless I need it and just kind of flick it.
This link is pretty good for tips: Lunge a Horse - wikiHow