First of all...Pun intended..
In Climbing everyone talks about "The Plateau". In running you might hear it as "hitting the wall" in reference to when you're running a long distance and you hit your breaking point. The two things are different slightly, in climbing your "Wall" is more of this looming number that is seemingly impossible.
I've had Bouldering Plateaus & Rope Plateaus, for bouldering it was the famous V5-V6 gap that many climbers struggle with as they turn from moderate to serious climbers. On Ropes my first "wall" was the 5.11 - 5.12 chasm that seems impassable to most. 5.12 is the antagonist in most rock climber's push to climbing harder, and it fights back hard for sure.
When you're first starting off climbing, a 5.12 seems physically impossible, the moves are usually very technical and the holds aren't the best. I have heard countless times "Dude, I don't know how in the world you do those 12's". The answer is that I couldn't and sometimes still can't do them, I have to keep climbing them to get them. One day I just decided to start climbing 5.12s and I sucked at it, like hardcore... but that's the point. Rock climbing is funny, in that you can climb 5 moves of a 5.13d and fall and have learned more than "On-Siting" fifty 5.11s. My mentor Mario says all the time; "At some point you don't get any stronger, you just get smarter." and it's so true, I mean I train all the time to get stronger of course, but the time I put into falling over and over again on 5.12s made me smart enough to send them now.
In climbing if you're not failing constantly, then you're not training right. I remember watching Mario climbing a route at Reimers Ranch in Austin on my very first climbing trip, it's called Pay the Pump and it's a 50 foot roof, and I thought to myself "That is absolutely impossible, he is a mutant" and now I've gotten the full roof pieced together (Check the vid). It's not like I waited 5 years to go try out this insane 5.13b, I went out and worked the moves over and over and over and over until I memorized every intricate heel hook and jug hold.
Basically the morale of the story is nothing in climbing is given to you. The best part of it to me is getting to go out and surprise myself when I try something I think is crazy hard and I get to climb it into submission