To Become a Man of Action
Starting in the mid to late 1950's Mishima had started to become an avid bodybuilder. Initially he had started this training as a way of ridding himself of physical ailments that had plagued him since childhood. Even as a child, Mishima had never been a very healthy person. His experience with bodybuilding in his late 30's was probably the first time in his life that he knew what it felt like to be a strong person. Mishima was fanatical about his weight training. He went as far to make non-interference in his physical training schedule a precondition to his marrying his future wife Yoko Sugiyama.
The result of Mishima's experience with weight training was his book length essay "Sun and Steel". The book was published towards the end of Mishima's life(1968). It is a non-fiction work that deals on the surface with physical training and the relationship between men. But it gives great insight into the kind of person that Mishima would become by the end of his life. His obsession with becoming a "man of action" and his dislike of all things intellectual are stated repeatedly throughout the book.
What weight training really gave Mishima was a means to reinvent himself. To remake himself into the image of a warrior, even though he had earlier cringed at the possibility of service in the Japanese army during World War II. "Sun and Steel" paints a very romanticized idea of life in the military ranks.