During a workshop I took from Aziza she offered a tip for sustaining a shimmy through her 20 minute shimmy which I found really helpful. She suggested focusing on different body parts at different times. For example, focusing on your heels pushing into the floor, or your knees moving past each other, or your glutes working, or your butt wiggling away, or your hips moving up and down, or the side-to-side rhythm of your belly button and stomach. Anytime you feel your shimmy starting to falter focus on a different part of your body.
Hope this helps.

Tammy,
Aziza's students have done that work out for a long time... they were not just doing it for the first time. You will get there. Start with this suggestion from a local teacher who studied w/Aziza...Kajmir said take all you favorite songs [belly dance, pop, top 40 whatever] and do 1 thing for the entire song. She said it takes 8 minutes for you muscle to learn it.. so shimmy for a song, then shift to chest slides, then a shimmy again, then hip slides.. and so on. This is all called "drilling" you will get there.
On the hyperextension - NEVER EVER do it. You should be able to control your stop and start. If you can't , then go slower until you figure it out. The straight leg is a very relaxed shimmy. legs going and everything elsa just flopp'in around and relaxed. The more relaxed you are the easier that shimmy is.
Good luck ! just practice.

Hi Tammy, from the angle it is a little hard to tell about the legs but I agree with the other ladies, keep your knees soft and don't snap them back.

A couple of things you could try, instead of going full speed, try slowing them down and see how long you go. It takes a far amount of stamina to go full speed for 20 minutes! Another thing to try is to take your shimmy to full speed and as soon as you feel like you start to lose it, slow it down, get control and try again. I find the hardest thing to do is to relax & some days it will feel easier than others. Just stick with it and you'll get it.

There's some basic physics that can make shimmies difficult: there has to be a constant, even and equal "wave" coming from each leg. Since no one has two identical legs to start with, part of the work of achieving a good shimmy is going slowly with excellent form to assess what's going on with your legs. Your ankle tendons might be tighter on one side, your quads stronger on one side, maybe one of your feet rolls in or out, etc. etc. All these factors can make an uneven movement, and then the waves from the two legs will cancel each other out. You have to work with a teacher with a sharp eye to figure this stuff out. Some you can feel, most you can't. A good Iyengar style yoga teacher will also help with muscle and skeletal balance.

In the absense of help, though, you should still practice slowly with the best form you can muster. If you practice too fast, you'll drill bad habits of unevenness and tension into your shimmy, and it's very hard to unlearn. It's the same for musicians who want to learn to play scales and tremelos quickly. You first have to go slowly and evenly, before introducing speed.