A version of this is the quote, "you are the average of the 5 people you spend the most time around".
Noting the effects on fitness, eating habits, depression, and more.
I definitely feel like a "Harriet" here, because I'm pretty sure I've literally said those words to other people in the Bay Area.
Paul Graham says that cities send subtle messages about what your ambitions should be—different ones tell you to be richer, or be smarter, or to live better. I have lately been feeling like the same is true of people, and groups of people, and TV shows, and songs, and workplaces, and Twitter, and places you sit down to get a quick drink.
Obviously people (and all these other things) explicitly tell you to do different things sometimes. But I think there are subtler suggestions, both about what is valuable, and about what the world is like.
Some examples, mostly from people I know, anonymized:
I had thought in the abstract that people around influence a person, but lately I more viscerally anticipate it, and shy away from some of the influences.
It’s dinner time, so I won’t elaborate further. Does this fit your experience?