For me, being right below the burn limit is where the most fun is, the most growth is, and where I'm most likely to hit a state of 'flow'. Some of the best week

For me, being right below the burn limit is where the most fun is, the most growth is, and where I'm most likely to hit a state of 'flow'. Some of the best weeks of my life have been 16 hour days of coding, taking breaks only for food and recovery walks. (all driven internally). There's an incredible joy that comes out of pushing yourself exactly as hard as you can tolerate and achieving your exact maximum productivity. And there's a lot of joy that comes from looking at the things you build as a result. I also did this last summer with hiking. In the space of about two months, I worked my way up from 3-5 mile hikes to day long, 40 mile hikes in 95 degree weather. I enjoyed it immensely. So perhaps there's no law that "you should work exactly enough that you don't burn out", but there's a lot of value in being able to be in that spot.