'Zuck told me to play the long game. I wish I had listened': OpenAI's Fidji Simo on her biggest career regret

Fidji Simo, who stepped down as OpenAI's CEO of Applications on Thursday, has opened up about living with a chronic illness and shared a piece of health advice she once received from Meta CEO Mark Zuckerberg—advice she now says she wishes she had followed.

According to Business Insider, Simo revealed in a social media post that she has been living with postural orthostatic tachycardia syndrome (POTS) for the past seven years. Reflecting on her career and health journey, she said she became ill while working at Facebook, where she spent a decade in various leadership roles.

'I immediately said no': Fidji Simo reflects on turning down medical leave

In her post, Simo said that despite repeated encouragement from doctors, colleagues, friends and loved ones to slow down, she continued to prioritise work.

"Over the years, doctors, friends, colleagues, and loved ones encouraged me to slow down," she wrote. “Two years after I got sick, Facebook offered me the opportunity to take a full year of medical leave. I didn't even pause to consider it. I immediately said no. At the time, Zuck told me I should play the long game. I wish I had listened.”

She added, “Looking back, I realize that a lot of what made me successful also made this decision incredibly difficult.”

Simo said her determination and willingness to seize opportunities helped her go from a small town in southern France to achieving more than she had imagined possible by the age of 40. However, she said her perspective on success has evolved.

"But what I'm learning now is that grit and endurance are not the only skills required to have impact over decades. Sometimes the harder thing is to stop, listen, and trust that taking care of yourself today makes it possible to contribute for much longer tomorrow," she wrote.

What is POTS?

Postural orthostatic tachycardia syndrome (POTS) is a disorder affecting the autonomic nervous system, which controls involuntary bodily functions such as heart rate. Symptoms are typically triggered when a person moves from sitting to standing and can significantly affect daily life.

Common symptoms include chronic fatigue, dizziness, heart palpitations, sweating, nausea, fainting and headaches.

According to a 2026 review published in Heart, Lung and Circulation, POTS can be difficult to diagnose because its symptoms overlap with several other medical conditions. The review also noted that there are no specific medications to treat the disorder, and management varies from patient to patient.

Describing the contrast between her work and her health, Simo wrote that it felt "jarring" to spend her days at OpenAI building what she believes is the future while "navigating a disabling disease that still has no cure."

She said she will transition from her role as CEO of Applications to a part-time advisory position.

OpenAI CEO Sam Altman reshared Simo's post on X and wrote: "i am really sad about this and very grateful for all fidji has done for openai, and even grateful for her friendship and who she is as a person. we all wish her the best for a speedy recovery. this sucks."

Ending her statement, Simo wrote: "For now, my focus is recovery. But my belief in the potential of technology to solve deeply human problems has never been stronger."

Who is Fidji Simo?

Fidji Simo holds a Master of Science in Management from HEC Paris and another Master's degree in Business/Commerce from the UCLA Anderson School of Management.

Before joining OpenAI, she served as the Chief Executive Officer of Instacart. Her career also includes more than a decade at Facebook, where she held several leadership roles in product management before becoming the head of the Facebook app.

She has also served on the boards of Shopify, Cirque du Soleil Entertainment Group and OpenAI, while co-founding the Metrodora Institute and ChronicleBio. In 2025, she joined OpenAI as CEO, AGI Deployment, before later serving as CEO of Applications.