2024 my wife and I did a startup together. We worked almost every hour we were awake, 16-18 hours a day, 7 days a week. We ate, we went for an hour's walk a day, the rest of the time I was programming. For 9 months. Never worked so hard in my life before. And, not a lick of burnout during that time, not a moment of it, where I've been burned out by 6 hour work days at other organizations. If you're energized by something, I think that protects you from burnout.