保重 bǎozhòng to take care of oneself

How to remember 保重: 保 to protect + 重 heavy = to take care of oneself.

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To take care of one's health - used almost exclusively as a parting well-wish: 你多保重 (nǐ duō bǎozhòng) take good care of yourself.
A warm, slightly formal farewell, especially when parting for a long time or when someone is unwell.
Not for daily 'be careful' (that's 小心); 保重 is specifically about tending your own wellbeing over time.