to develop an emotional or physical state that you feel strongly, after a period of effort or time

We worked up a real appetite climbing in the mountains. 我们突然很想爬山。

It's strange, but I can't work up any enthusiasm for going on this trip. 很奇怪，这次旅行激不起我的任何热情。

to make yourself or another person feel upset or feel strong emotions

Try not to work yourself up about the exams. 尽量不要因为考试而情绪激动。

Nationalist speeches worked the crowd up into a frenzy. 民族主义者们的演讲把听众的情绪煽动得疯狂起来。