1. He had to be of very strong constitution, to put up with such exhausting mental labour.
    他必须具有极其强壮的体质，不然应付不了如此耗费精力的脑力劳动。

2. I argued that if I spent less time exhausting myself at exercises in the morning, I would keep my mind fresh for reading when I got home from work.
    我辩解说，早晨少耗费精力锻炼，晚上下班回家看书时头脑更清醒些。