^ Or not depending on what you're asking LOL... and don't forget your hips.. if you aren't "straight" neither will your horse be (just like when you ride)
Lunging and riding present some really interesting parallels... and is the reason I've begun to include teaching lunging along with riding for new riders.
I suppose one of the biggest things to learn and get the hang of is this - the horse isn't "wrong". If it's not doing something you expected, stop and take a look at you before you get "mad" and just start using your whip. Occasionally you will come across a horse that just says "no", but usually they are doing what they are doing because they thought you meant something else.
Ideally, you should be able to lunge with nothing but the horse and you. We use the line and whip as tools to help us maintain steady communication... but they aren't really "necessary" once you have the hang of it.