Why "保重" means "take care"? As far as I have learnt, for each Chinese word with more than one character, its meaning is formed from that of each character which it comprises. However, I cannot understand how the meaning of 保重 is formed this way. I thought that:


保 = to protect
重 = important


what would 保 and 重 mean for this word? How does it go from "to protect the important one" to "take care"?

Thanks in advance!
It is true that this word originally comes from 《晋书·夏侯湛传》：“方将保重啬神，独善其身。”
But we use it in situation of farewell. 珍重 is heavier than 保重。 珍重包含了珍惜cherish.

保 是保住，保持，守 。 keep， reserve probably.

重 has two tones:


zhòng 是分量较大，与“轻”相反。 large amount or heavy. opposite with light. 很重，举重。
chóng means again. doubled. 重复，重播。


In the phrase 保重 is zhòng. In my appoint: strong power. strength.

Does it make sense? (Reference.)