Calm Like Water in Chinese / Japanese...

上善若水 is a quote that is sometimes presented as “Be like water.”

However, this is an ancient quote from the great philosopher Lao Tzu. It suggests that the ultimate goodness and purity (in the world) is water. Many take this as a suggestion to be like pure/good water.

水の心 is the Japanese Buddhist and martial arts phrase, “Mizu no Kokoro,” which means “mind like water” or “heart of water.”

The phrase is a metaphor describing the pond that clearly reflects its surroundings when calm but whose images are obscured once a pebble is dropped into its waters.

若水 is part of a very old saying from Lao Tzu.

In these two characters, there is a suggestion to be like water. The full phrase is about the goodness and purity of water. So, when this suggests being like water, it is actually a suggestion to be a good person (one who does not dishonor himself/herself, etc.).

像水一樣 is a short quote from a much longer statement by Bruce Lee.

He summarized how people should be flexible to all circumstances, attacks, or situations. In the end, he exclaims, “Be like water, my friend.” 像水一樣 is the “Be like water” part alone since that seems to be what most people want.