Plain Facts for Old and Young by John Harvey Kellogg

3. Avoid watching for symptoms. Ills are greatly exaggerated by

dwelling upon them. One can easily imagine himself getting worse when he is really getting better. Indeed, one can make himself sick by dwelling upon insignificant symptoms. Fix upon a course to pursue for recovery, firmly resolve to comply with every requirement necessary to insure success, and then let the mind be entirely at rest respecting the result.