to bend to a task and spare no effort; striving to the utmost

To be both mentally and physically exhausted.

mentally and physically exhausted; worn out in body and soul

to exert one's utmost effort; to work until one is exhausted, typically in service of a greater cause.

to be completely drained both emotionally and physically

To dedicate oneself heart and soul to a task and work tirelessly until the day one dies.