It's simple really. Who you are on the inside is what you will see on the outside. Consider:
Any idea, person or object can be a Medicine Wheel, a mirror for man.
Or this from Anais Nin:
We don't see the world as it is, we see it as we are.
Think about it. If you've just won the lottery (or the girl or the guy or the promotion) the world is bright and cheery. Everybody seems friendly. Life is good. The world is good.
Conversely of course, when things are going against you (losing the girl or the guy, getting fired), the world is a mess of meanness, pettiness and hatred.
And to know this principle of 'life as a mirror' is just so helpful. Whatever it is you're feeling or experiencing, do not make the mistake of looking at externals for the answers as to why. The answers are all inside you. Is something scaring you? No, nothing's scaring you. The fear is in you, and it's just found a convenient object to attach to. And it's the same with everything. We project what is inside us onto other people, situations and things.
Know thyself, Socrates said so long ago. That's what it all boils down to. And no, it's not easy to know yourself. It's work. You need to pay attention. To live consciously. To be awake. But it is so very worth it.
If you can just observe what you are and move with it, then you will find that it is possible to go infinitely far.