Here is a video that explains a 100-year-old exercise routine created by J.P. Muller in 1904 in his book, My System, 15 Minutes Exercise A Day For Health’s Sake. It may still be one of the best-selling exercise books ever (maybe two million copies in 25 languages), and it’s success rocketed Muller from his obscure role as a Danish gym instructor to a huge celebrity with a training center.

Muller believed that it’s your fault if you are sickly or if you are weak. By following his exercises, you can become an Iron Man.

And here is a link to the entire book and the 18 exercises. Scroll down to the Contents and then click on pages 64 and 88. Or more easily, refer to this link describing just the exercises.

Franz Kafka was a fanatical Müller follower. He would do the movements, fully naked, in his window, twice each day, whirling his arms and twisting this way and that, practicing the same hops and isolations advocated with similar vigor by my family. Indeed, My System became an integral piece of Kafka’s obsession with the body. When Müller’s women’s pamphlet was published, in 1913, Kafka sent a copy to his fiancée, Felice Bauer, recommending she pick up a daily practice as well. “If they bore you, it shows you are not doing them properly,” he wrote.

Mark Anderson, the author of Kafka’s Clothes and a professor of German and comparative literature at Columbia, argues that the author was likely drawn to Müller’s unabashed commentaries on the crush of modern life. (“The town office type is often a sad phenomenon … prematurely bent, with shoulders and hips awry from his dislocating position on the office-stool, pale, with pimply face.”) The system also promised benefits for artists and writers (“geniuses who have no thoughts for their bodies”), and Kafka appears to have shared Müller’s pleasure in the naked body. (Kafka himself did a short stint at a nudist summer colony and often sunbathed nude at home—at least until his tuberculosis caught up with him.)