Through his personal study and experimentation Wattles claimed to have discovered the truth of New Thought principles and put them into practice in his own life. He also advocated the then-popular health theories of "The Great Masticator" Horace Fletcher as well as the "No-Breakfast Plan" of Edward Hooker Dewey, which he claimed to have applied to his own life. He wrote books outlining these principles and practices, giving them titles that described their content, such as "Health Through New Thought and Fasting" and "The Science of Being Great". His daughter Florence recalled that "he lived every page" of his books.