A triathlon consists of three disciplines, each with its own specific challenges and demands. In addition, every athlete is unique and has individual strengths and weaknesses. For most people, running a standalone marathon already seems nearly impossible. For the triathlon community, however, it is “only” the final segment of an Ironman. In this article, we will outline the differences and specific characteristics of a standalone marathon compared to the marathon at the end of an Ironman. We will also provide guidance on how to approach the Ironman marathon under the best possible conditions.