Lilian Weng, a cofounder of Thinking Machines Lab and former OpenAI safety executive, resigned Tuesday, citing illness worsened by startup stress. In a note to colleagues, she wrote that seven months of recurring illness, made worse by the relentless pace of startup life, had left her unable to give the job the full effort she felt it demanded. "After thinking about it for several months, I ultimately have to admit that the amount of consistent stress and workload have pushed me beyond what my health can sustain physically," Weng wrote, adding she hopes to return in a more scoped role at a calmer workplace. The article also outlines strategies from 10 other business leaders to stave off burnout: Snap CEO Evan Spiegel protects Sundays for church, brunch, and time with his four kids; Michael Dell emphasizes a mix of working, playing, and relaxing; Ring founder Jamie Siminoff practices "work-life fusion"; Arianna Huffington, after collapsing from exhaustion, founded Thrive Global focused on well-being; Jeff Bezos frames eight hours of sleep as a fiduciary duty; Indra Nooyi treats each day as a series of explicit trade-offs among CEO, wife, and mother; and Sheryl Sandberg defended leaving the office at 5:30 p.m.