The next time you are telling someone something, stop, and think about how much you don't know about what you are talking about. It is so easy, especially when we get older and supposedly wiser, to "believe" we have the answers.
Personally and professionally, we feel we know the answers. With confidence, we take a stand on an issue or topic. It is at that moment, we need to stop and consider how much we don't know. Open up our minds to the possibility that there is probably so much we don't know on the issue or topic. That can be difficult, because we want to believe we know. But we don't.
If we open our minds to the notion that we are not the expert, that there are people out there that know more, perhaps even the person we are talking with/to, it allows us to want to learn more. If we want to learn more, we become more pro-active in seeking information from those we interact with.
If you have children, you feel you are supposed to know it all. When they come to you for advice or help, you might feel it is your job to share your expertise/wisdom. That's fine, just remember, you don't know it all, do you? How would that exchange with you child be different if you were asking yourself, "do I really know what I am talking about?". I hope the answer is a mix of yes and no.
If you are in an interview or networking, you want to appear knowledgeable and confident. You don't, however, know it all. That results in arrogance. Keep an open mind, remember, you don't know it all.
Adopt the "life long learner" mentality. It keeps you alert and humble and much more enjoyable to be around.