Force is not a muscle nor a detectable organ in human anatomy. However, to live it is necessary to have the ability to carry loads and to withstand impacts, and also to endure setbacks. In an invisible place between the mind and the heart, perhaps in the soul, dwells the strength that allows us to move forward and achieve goals. "The Challenge on Wheels" is the story of Guillermo Ling, whose life changed in the blink of an eye: as a result of a random event, he was left in a wheelchair. Unlike Hercules, a mythological figure famous for his vigor and energy, Guillermo did not confront the Nemean Lion or kill the Cretan Bull. However, he has had to endure many obstacles, and he has succeeded. As the philosopher Seneca, the representative of Stoicism, rightly said: "Only in adverse fortune can the great lessons of heroism be found". These pages collect the memoirs of whom, without being able to walk, will inspire others in the same circumstances. At the end of the steep path he had to travel, Guillermo would leave tracks... not with his footsteps, but with his actions.