I bought this a few months ago at my sensei's suggestion. I've been doing yoga on and off for a while, and I often use yoga as a way to build strength and flexibility to enhance my karate studies. But with one thing and another, I didn't get around to trying it for a while. A free days ago, however, I was working it with a friend and the tabata workout I was going to stream wouldn't stream. My friend suggested we try this workout since I hadn't done it before.Let me tell you, the tabatas would have been easier.I'm a physically strong woman in fairly good shape, but this workout had me crying. It exposed weakness in muscle groups I didn't even know I had, and it had my arms and legs shaking by the end. The best part? It did this while promoting stretching and flexibility throughout the body.This is a terrific workout. And in the end, that matters more than all the cheesy soundtracks in the world. I have added it permanently to my weekly rotation.That said, ***this workout's not for complete fitness beginners***. My friend is just starting her fitness journey and she couldn't get through it, even with the modifications. Many common exercises, like pushups and planks, demand good form to see real results. 'Cheating' the form to make the pose easier may help you get through your set, but it won't help you build muscle or fitness. This workout is the same. The original and modified poses must be done correctly to see the promised results. This takes a certain level of strength. If you are uncertain of your fitness level, I would start with basic strength building calisthenics and beginner yoga classes. I like to use the Down Dog app (downdogapp.com) for variety and workouts tailored to my level and needs.