Your body cannot read your schedule, but it can certainly respond to it.

Your calendar is an agreement made between you and other people, and your body was not consulted. It responds anyway, to the late nights, the missed meals, the months without a break, and it responds regardless of how reasonable the schedule looked when you agreed to it. There is no arrangement in which the diary wins that argument permanently.

Before accepting the next commitment, ask what it will require physically rather than only how many hours it takes. If the answer is more than you have, negotiate now. The body will collect either way.