When Fidji Simo stepped down as OpenAI's CEO of applications, she reflected publicly on a key health lesson learned through experience.

Simo has lived with postural orthostatic tachycardia syndrome, or POTS, for seven years. She shared the news on social media the day of her resignation.

The condition began while she held various roles at Facebook over a decade-long career.

"Doctors, friends, colleagues, and family urged me to slow down over the years," she wrote. "Facebook offered a full year of medical leave two years after I became ill, yet I turned it down right away. Zuckerberg advised me to play the long game, and I wish I had taken that suggestion."

She noted that many traits behind her success also made the choice to rest especially tough.

Zuckerberg has not yet commented on the matter.

Simo described how seizing every opportunity helped her rise from a small town in southern France to notable achievements by age 40.

"I am learning that grit and endurance alone do not sustain impact over decades," she said. "Sometimes the tougher step is to pause, listen, and trust that caring for yourself now allows greater contributions later."

What is POTS?

POTS affects the autonomic nervous system that controls involuntary functions such as heart rate. Symptoms appear when someone moves from sitting to standing and can severely limit daily life.

Common effects include ongoing fatigue, heart palpitations, dizziness, sweating, nausea, fainting, and headaches.

The condition shares traits with many other illnesses, which can delay diagnosis. Treatment is personalized since no single medication addresses it for everyone.

Simo described the contrast of advancing future technology at OpenAI while managing a serious illness without a cure.

She will shift to a part-time advisory role at the company.

OpenAI CEO Sam Altman reposted her message, expressing sadness and gratitude for her contributions and friendship while wishing her a quick recovery.

Simo closed by stating her focus remains on recovery, though her confidence in technology solving major human challenges stays strong.