I started taking classes with Gerren after he subbed for a regular teacher of mine. I was hooked. 30/60/90 is INTENSE, but it's the BEST workout I've ever experienced. Gerren is definitely a no-nonsense instructor, but he still approaches every class with a sense of humor. Gerren's class isn't a place to hide. His eyes are always open, and he will tell you if you need to step up your game, which I love!