Indeed, the mind never makes a great and successful effort, without a corresponding energy of the body.
 Henry David Thoreau, A Week on the Concord and Merrimack Rivers (1849). copy citation

Context

“and so will the strokes of that scholar’s pen, which at evening record the story of the day, ring soberly, yet cheerily, on the ear of the reader, long after the echoes of his axe have died away. The scholar may be sure that he writes the tougher truth for the calluses on his palms. They give firmness to the sentence. Indeed, the mind never makes a great and successful effort, without a corresponding energy of the body. We are often struck by the force and precision of style to which hard-working men, unpractised in writing, easily attain when required to make the effort. As if plainness, and vigor, and sincerity, the ornaments of style, were better learned on the farm and in the workshop, than in the schools.” source