The human body can adapt to extraordinary stress, but this DW film asks where that capacity actually ends. Stefan Santifaller, a former competitive athlete, describes pushing his training so hard in his youth that he became seriously ill, an experience that forced him to rebuild his life around different limits. Markus Rehm's story runs alongside his: he lost his lower leg in an accident as a young man and is now a world champion para-long jumper, and the film follows how he retrained his body and mind to compete at the highest level on a prosthetic blade. Doctors and researchers explain what happens physiologically when the body hits overload, from muscle tension and rapid heartbeat to sleep loss, dizziness, and mental blocks, framing these as warning signals rather than failures. The film moves between interviews, training footage, and everyday scenarios of stress and burnout, building a picture of resilience as something trainable but not limitless, and asking what it costs to find out exactly where the line sits.