1. Make the athlete sprite move right and left when the right and left arrow keys are pressed using "if" blocks and "key pressed" events.
  2. Add a "set rotation style" block to keep the sprite from flipping upside-down.
  3. Make the sprite move in the direction it's facing with a "move" block.
  4. Use a "forever" loop to make the athlete keep moving as long as a key is pressed.
  5. Start the game with a "when flag clicked" event.