A silhouetted figure stands against a backdrop of glowing city lights, then the scene cuts to a man in a weighted vest screaming with effort during a workout, followed by a man performing a push-up on a weighted sled, then a group of sprinters launching from the starting blocks on a track, then a close-up of a runner's prosthetic leg and foot in motion, and finally a speed skater gliding at high speed on an ice rink.