A challenge can be looked at in several ways, something to fear, something to accept defeat for or something to conquer. Everyday we are faced with challenges even as small as "how do I feel or rather what do I do about the things I don't like in me".
Same instance we can look at this "thing" or mountain and say "be removed, I love me". You can say "mountain you are unchangable and I can't do anything about you". You can also say, mountain if I remove you I will have nothing to complain about.
The wife of KRS1 has a quote that says, "blame is"
You are your ultimate challenge. We look at everything around us to change. But nature (mountain) says to you, "why should I change for you if you won't even be moved within your own self".
Meet your ultimate challenge as she stares right back at you!