Indian navy personnel mark the fifth International Day of Yoga on the deck of a decommissioned aircraft carrier in Mumbai on Friday. (Divyakant Solanki/EPA-EFE/Shutterstock)

On submarines and on mountaintops, in schools and in parks, by the dozens and by the thousands, Indians celebrated an ancient tradition that grew into a global phenomenon.

Friday marked the fifth International Day of Yoga, a yearly event created by Prime Minister Narendra Modi to highlight yoga within India and around the world.

While previous Indian prime ministers practiced yoga, none have embraced it quite like Modi. He practices yoga daily and every year on June 21 participates in a massive outdoor yoga session. He has extolled yoga as a way to improve health and concentration, reduce stress and promote peace.

Of course, there is more to this than personal well-being. Modi’s strenuous promotion of yoga is part of a broader push to tap Indian traditions as a source of national pride and international influence. 

The fact that a physical, mental and spiritual practice that originated in India is now a multibillion-dollar industry around the globe has not escaped the government’s attention. 

Prime Minister Narendra Modi takes part in a mass yoga event Friday in Ranchi, in northeast India. (India's Press Information Bureau/AFP/Getty Images)

Yoga is source of tourism for India and also an opportunity for Modi — who recently won reelection in a landslide — to portray the country as a spiritual leader. He often speaks of his desire to turn India into a “vishwa guru,” a country that acts as guru, or teacher, to the world.

 Studiously absent in the official celebrations of the International Day of Yoga is any mention of Hinduism. “Yoga is for all and all are for yoga,” Modi tweeted Friday.

The question of yoga’s parentage, the product of thousands of years of history and multiple religious and geographic influences, is a complex one. 

 But its roots in ancient Hindu texts and philosophy make it a natural fit for a Hindu nationalist politician such as Modi. For politicians sharing Modi’s views, yoga’s origins and its enormous secular popularity add up to “the perfect vehicle to create a shared national consciousness,” wrote novelist Manil Suri

Yoga practitioners at the 15th-century Adalaj Stepwell in Adalaj, India, on Friday. (Sam Panthaky/AFP/Getty Images)

International Day of Yoga observers in Allahabad. (Sanjay Kanojia/AFP/Getty Images)

The popularity of the International Day of Yoga has spread to other countries as well. Here, people participate in a mass yoga session in Tel Aviv on Thursday. (Jack Guez/AFP/Getty Images)

Pakistani yoga practitioners on Thursday at a park in Lahore. (Arif Ali/AFP/Getty Images)

A yoga session Friday at the Victoria Memorial in Kolkata, India. (Piyal Adhikary/EPA-EFE/Shutterstock)

A yoga practitioner on the rocky crest of the ancient Kokino observatory in North Macedonia on Friday. (Robert Atanasovski/AFP/Getty Images)

People do yoga atop the London Eye as the sun rises Friday. (Henry Nicholls/Reuters)