Friends who grew up differently than you will stretch your brain more than any textbook.

People who grew up under different rules carry different defaults, and their ordinary assumptions will contradict yours in ways no book manages. A book presents another view. A friend makes you sit inside one, over months, until you can feel where your own certainties came from rather than just holding them.

Seek out the conversations where you are the one who has to ask what something means. Ask more and correct less. The discomfort of not being the expert in the room is where most of the widening happens.