The man who invented relaxation (2015)

If you want to really understand relaxation, try looking into tai chi and Qigong. These arts are profoundly rooted in relaxing in an extremely deep way. You don't realize just how much tension you have in your body, and it actually takes a long time to work through these layers of tension (which build up over our whole lives) until you can truly experience full relaxation.

I did yoga and zen meditation for years, but once I started practicing tai chi and Qigong, it was a whole different ball game. It's kind of hard to explain, because I was so completely unaware of just how deeply rooted and pervasive the stress and tension in my body was. Tai chi and Qigong have changed my life - I experience so much less chronic pain, and feel so much healthier and robust than I did with just yoga and seated meditation.

YMMV, as I got pretty lucky in finding an extraordinarily good teacher, but I cannot recommend it highly enough.

Iyengar yoga is the best kind of yoga out there. Iyengar yoga instructors are the best teachers of yoga (in the west) because they focus on precision and technique. Most of what people call "yoga" is total BS.