The brain is pre-programmed to repeat, and build upon repetitions. The mind, though, can be self-programmed to erase limiting beliefs, and enter fresh, useful codes into the computer system that is our brain.
The first boy was shocked and looked down at himself. He did look puny when compared to the other boy. The first boy then thought that maybe the second boy was right indeed. Maybe he was not fit enough to climb this tall a mountain. Maybe he should go back home.