i'm sure you know the same advice spilled from the amazingly reliable information source "man with habit podcast", but Sufficed to say, it isn't normally that relevant. sure go to the gym, eat well, sleep lots, drink water and meditate are all sound pieces of advice. But you shouldn't beat yourself up if you don't do all that.
if anything, I've found it best to just meditate. i don't mean in the way that modern, productivity gurus have co-opted. the way that it was in the past, quietly assessing, allowing thought without judgement and waiting for them to pass.
the point is to disconnect from what your mind is used to connecting to, your buzzing thoughts.
unfortunately they can be the largest cause of burnout to begin with. if you're not able to focus, then breath work meditation is going to feel like a chore. the first step her is becoming comfortable in silence.