I love this quote from Seneca that I found on the post, “Seneca on How to Fortify Yourself Against Fear and Misfortune,” by Maria Popova, on brainpickings.org:

Set aside a certain number of days, during which you shall be content with the scantiest and cheapest fare, with coarse and rough dress, saying to yourself the while: “Is this the condition that I feared?” It is precisely in times of immunity from care that the soul should toughen itself beforehand for occasions of greater stress, and it is while Fortune is kind that it should fortify itself against her violence. In days of peace the soldier performs maneuvers, throws up earthworks with no enemy in sight, and wearies himself by gratuitous toil, in order that he may be equal to unavoidable toil. If you would not have a man flinch when the crisis comes, train him before it comes.

I liken it to Pilot Season.  If you spend a LOT of time working like it’s Pilot Season when it’s NOT pilot season (“during which you shall be content with” working insanely hard, nailing like five pieces per day), then you’ll be in good shape during “greater stress” (Pilot Season).  “. . . it is while Fortune is kind that it should fortify itself against her violence. In days of peace the soldier performs maneuvers, throws up earthworks with no enemy in sight, and wearies himself by gratuitous toil, in order that he may be equal to unavoidable toil. If you would not have a man flinch when the crisis comes, train him before it comes.” 

Thank you, Brain Pickings!