Anyone telling you that is using a subtle form of gaslighting to manipulate you into believing what they believe, not into being more interesting. They also tend to be narcissists who have no real interest in you, and therefore don't know enough about you to make that judgement.
Hey, self improvement is a great thing, but I'd say just stop hanging out with people who say that. It's akin to telling someone "being gay is a phase" or "have you tried just not being schizophrenic". It's offensive to say someone's personality is boring and broken.
