Far too many people will run a marathon just for the sake of saying they’ve run a marathon in their lifetime. After finally crossing the finish line and collecting the medal you might ask them when they are going to run another and they usually respond by looking at you like you’re crazy! A few months later they’ve quit working out for good and are back where they started. Running one marathon does not give you a lifetime of fitness credibility. A lifetime of fitness credibility takes a lifetime of fitness.