Amusingly enough, yoga historians have discovered that pretty much all the yoga practiced today in India is actually derived from a secular exercise program from Victorian-era Sweden.
“Swedish gymnastics” was a system invented by one Pehr Henriik Ling. It included stretching, balance exercises, calisthenics, and massage. (Later, a Dutch guy named Mezger, inspired by Ling, invented the massage techniques which are now known as “Swedish massage.” Ling was popular.) British Army officers liked Swedish gymnastics, as well as a related system called Primitive Gymnastics by a Dane named Niels Bukh. They brought these exercises to India… where it eventually became yoga.
Briefly, what happened was that young progressive Indians who were interested in independence decided that they needed to build up the bodies of the Indian people by getting them to do modern exercises. They mostly learned Swedish gymnastics in YMCA’s in India.
But in order to make the exercise more attractive, they talked about it in terms of their Hindu beliefs. Some of them began to compare it to the ancient yogis, and even to claim that their yoga was the same thing.
As the generations went on, later Indian exercise fans made it more and more about religion, spiritual healing, sexual energies, and so forth, but the basic movements were still Swedish. So all the “kundalini” and Hindu stuff has actually been grafted on.
Maybe all you need is Swedish gymnastics and Danish “Primitive Gymnastics.” No need to do yoga.
Also you will note in the Yoga Journal article above that some Victorian exercise mavens had their own bunch of Western cultish weirdness. So we can’t blame Indians for all the drama…
(PS - Yup, I know all this info came out in 2010 and 2011, but it still doesn’t seem to be common knowledge.)
(PPS - Here’s a book about gymnastics by Niels Bukh.)