What is the central idea of ‘stress for success’

A pounding heart. Tense muscles. Sweat-beaded forehead. The sight of a coiled snake or a deep chasm might trigger such stress responses. These physical reactions signal that the body is prepared to deal with a life-threatening situation.

The central idea of success is you need to have stress to work for your goals and then when you've accomplished your goals then it's success and you've gone through a lot so take a break, but get back to your  goals again because goal will NEVER stop.  

(Hope this helps) Sky

d) the narrator even suggested that the white whale, moby d, was ubiquitous and present in every ocean at every moment.