Herb Elliott was asked this question by an interviewer: What is the key to achieving our very best performances in running? He responded, "We must realize we have much more strength in our body than we think. The key to that strength is the mind. The relationship between the mind and body is still something we are really just playing around with. We don't understand the enormous power that we have within us and that is touchable."
When Herb Elliott speaks on running everyone should pay very close attention. What he says above is quite similar to comments Yiannis Kouros has made in the past. I would add that the majority of us are the ones who are most critical and pessimistic in regards to what we are capable of doing. We must make it a point to stop imposing self created limitations on ourselves.