Ask HN: How to you optimize output while not burning out?

Earlier in my career I pushed myself to my limit, with not much care to not burn out; now I feel I can sustain productivity without being consistently past that overcommitment line - a subjective measure. The hardest part to me is having a clear shutdown routine, especially in days I did not fully solve whatever I set out to solve. And this seems an order of magnitude harder nowadays with AI.

How do you all manage this? Any resources?