You don't have to work very hard to figure out what these different facial expressions mean.

你不必努力地去学习,去辨析不同面部表情的含义。

耶鲁公开课 - 心理学导论课程节选

Or perhaps, you could set a goal to lose weight and you could work very hard.

又或者，你制定了一个减肥的目标，你为此而努力坚持着。

I'm frustrated 课堂 - SpeakingMax英语口语达人