The document discusses how human limits and what is believed to be possible are constantly being pushed through the actions of role models. It argues that improvements in things like world records over time are not due to technology or nutrition, but to changes in human belief about what can be achieved. The key points are that doing small amounts regularly can help make difficult or impossible tasks become easy, as belief and ability reinforce each other, and the body can be used to prove to oneself what is possible through consistent practice of challenges.