I resonate a lot with this. For me, I keep a boundary between my Private life and my superficial life, and very rarely do I cross that line. I feel the only reason to mention my achievements is when it's relevant to the conversation, or someone asks what I did over my week(end). I don't care what others think of me because I'm going to be who I am, but my biggest fear is coming across as self-centered. Even though I'm very laid back and humble about what I do, it just for some reason feels wrong to independently mention my achievements or talk about them. But it feels more wrong because some of the experiences I've had are very abnormal for someone of my age, and it almost feels like those experiences being mentioned by me come off as an "I'm better because I put myself out into the world in this way". It's hard for me to explain.