说出来的话是药；闷在心里的话是病。Shuō chulai de huà shi yào; mēn zài xīn li de huà shi bìng.
Literally means: if you have something on your mind, it’s better to talk to your friends and your loved ones; they can help you solve your problems, just like drugs can cure illnesses; if you do not let it out, and keep it to yourself, the distress will catch up with you.
The nearest English equivalent may be: "Laughter is the best medicine", but the idea in Chinese is considerably different.
Example sentence: 如果你有了难处，最好和亲人朋友们谈谈，因为 “说出来的话是药；闷在心里的话是病”。
Rúguǒ nǐ yǒu le nánchu, zuì hǎo hé qīnrén péngyoumen tántan, yīnwèi “Shuō chulai de huà shi yào; mēn zài xīn li de huà shi bìng”.
“If you have a problem, it's better for you to talk to your friends and loved ones. As the saying goes, “speaking out is as good as medicine, whereas keeping things to yourself invites distress”.