Imagine the frontiers that Tyson describes above as borders. There's the land of where you've been, and the land beyond, which is the land which you've never been.
Some people see these borders and shrink from them. After all, they're borders. They're there for a reason. You're not supposed to go past them. Going past the borders is out of bounds, and that's bad.
The reasons for it being bad are myriad. Someone told you it was bad, so you believe it. Mom and Dad will be mad at you. Your family will disown you. Your husband won't be pleased. Your wife will complain. Your girlfriend will break up with you. Your boyfriend will hate you. Your friends will think less of you. God forbids it.
Fear is what keeps people from exploring those frontiers of discovery and imagination. It's always fear.
Fear of reprisals.
Fear of learning that everything they've ever known is wrong and they might have to relearn.
Fear of the work involved in trying to discover whatever it is just past those borders.
Fear of realizing their dreams and fantasies of what they wish they could be and who they wish they were are simply wishes.
Fear of being bad at something.
Fear of being good at something, and realizing they have been wasting their lives doing whatever else they've been doing.
Fear of finding out Mom and Dad and family and husbands and wives and girlfriends and boyfriends and God just might not be who they should spend the rest of their lives with, because they're afraid of being alone.
To say "so stop being afraid" is the greatest lie any human could tell another. Because the truth is, we're all afraid. No exceptions. It's just that some of us are thinking in voices that are not our own, We're listening to the wrong audio track in our own heads.
The trick is not ending fear. It's staring it right in the face, gritting your teeth, and taking one step forward. And when that doesn't kill you, taking another step.
It's not easy. In fact, it's goddamn hard. It's hard to get up the courage to even go to the edge of what you know, whether it be a new subject, a new life endeavor, or even getting to know someone you've never known.
But it's okay to be afraid. Fear is natural. It shows up and forces you to be alert. You will be afraid. You will want to turn around. You will want to go back to comfortable, to warm, to familiar. And that's okay, too... Just don't lament your life when you do.
To get something you've never had, you have to do something you've never done.
Go on. Walk right up to that border. Look at it. Consider it. Take your time. And when you're ready, take one step.