Never frown in bad mood, who knows some guy might fall in love with your smile.

即使不开心也不要皱眉，因为你永远不知道谁会爱上你的笑容...

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And their world is about how much money they are spending on vacation, who's in bad mood that day, or whether or not they're guilty about having a cleaning lady.

他们所有的问题只不过是度假花多少钱啦，谁今儿心情不好啦，雇个清洁工要不要有罪恶感什么的。

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Forcing yourself to smile can boost your mood: Psychologists have found that even if you're in bad mood, you can instantly lift your spirits by forcing yourself to smile.

勉强自己笑可以振奋精神：心理学家发现，即使你心情很糟，只要强迫自己笑出来，就会马上情绪高涨。

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If you're tired or stressed out or in a bad mood or, you know, full of rage.

如果你很累、压力很大、心情不好，或是很愤怒的时候，

会打棒球吗？ - SpeakingMax英语口语达人

Graniss reminds us that our emotions can get the best of us not only when we are in a bad mood but also when we are in a good mood.

FORBES: Top 10 Emotional Intelligence Moments of 2012

On the occasion where Miller was in a bad mood, he would slowly sip a neat Old Grand Dad.

FORBES: Friends and Colleagues Pay Tribute to Baseball's Marvin Miller, a Giant of American Labor

It's like when someone sends you a perfectly nice e-mail but you're in a bad mood so it appears rude.

BBC: Why are round-robin letters so annoying?