Why is the “20 MILE MARCH” key to consistent performance?

The following self help and motivational insight has been adopted from Jim Collins’s book Great by Choice..

“If you want to achieve consistent performance, you need both parts of a 20 Mile March: a lower bound and an upper bound, a hurdle that you jump over and a ceiling that you will not rise above, the ambition to achieve and the self-control to hold back.  ”

Adopted from Jim Collins’s book Great by Choice

Having the discipline to remain within the bounds of the 20 mile march is what differentiates consistent performers from others.