Become one with yourself. When your body says something, listen to it. When your mind is burnt out, respect that. We can either work with or against ourselves; you choose which route you’d like to take.
When you need to, take a break. Really. Burning out is a thing, being overworked exists, and chronic fatigue happens. You must learn to listen to your mind and body; when they tell you you’ve had enough, that’s it; you’ve had enough. Working hard is important, however be careful not to overdo it; for the good of your own mind, body, and soul.