Where I've found the most personal growth has been in continually re-learning the strangeness of other people's inner worlds. I try to imagine each person I meet inhabits an alternate universe, just as rich and nuanced as I feel my own is. So a healthy spirit of exploration and generosity helps, although it requires treating yourself the same.
A good shorthand I heard a long time ago from someone else on HN: when someone is expressing a problem to you, consider it your job to build a picture of their mental state that you can repeat back to them and have them recognize as their own. Good luck!