John Anderson has felt terrible quite a bit during ultramarathons. But he’d never experienced nirvana until he was deep into the Tor des Glaciers, an unmarked 450K with more than 100,000 feet of climbing. That’s like running the Hardrock 100—largely considered one of the hardest ultras on the planet—three times.

It really was the most intense hallucination he’d ever experienced.

“I look down and my body starts disappearing. My arms and then my legs, and then I couldn’t see my body anymore,” he said. “I thought I had achieved nirvana and went spiritual and had ceased to exist.”

Anderson is the medical director of the Broken Arrow Skyrace. He is an ER doctor and helped found Tahoe Wilderness Medicine. Every year, he hosts the Western States Health and Athletics Conference with Andy Pasternak, the  medical director of the Western States 100. But Anderson leans on his vast experience as an ultrarunner as much as his medical knowledge, mostly because his experiences provide new things to study and learn.

He’s won the Tahoe Rim 50-miler and finished top 10 at the Hardrock 100. Working races, in addition to running them, has exposed him to medical problems he may not see anywhere else, even in the ER.