When combined, the characters literally translate to: “to be accustomed to (习) [something] and take (以) it to be (为) normal (常).”
习以为常 touches upon a core aspect of Chinese philosophy and daily life: adaptation and resilience. The concept isn't inherently positive or negative; it's a pragmatic observation about human nature. In a culture that has weathered millennia of immense change, the ability to adapt and normalize new circumstances is seen as a vital survival trait. To an English speaker, the phrase might feel similar to “getting used to it” or “taking it for granted.” However, there's a key difference in framing.
The connotation of 习以为常 depends entirely on the context.