Rosa had been training for the marathon for six months. On the morning of the race, at kilometre eighteen, her knee started to ache. Not sharply — just a dull, persistent pull. She slowed. She looked at the crowd. She thought about the physio bill, the missed weekends, the early mornings. And then, quietly, without drama, she stepped off the course. She told herself it was sensible. She told herself a lot of things on the bus home. But what she couldn't stop thinking about was the moment she decided to give up — how easy it had been, and how heavy it felt afterwards.

The following year, Rosa lined up again. The knee held. At kilometre eighteen, the ache returned — familiar now, almost expected. She acknowledged it, adjusted her pace, and kept moving. At kilometre thirty, everything hurt. At kilometre thirty-eight, she stopped thinking about the finish line and focused only on the next step. One step. Then another. When she finally crossed, she didn't raise her arms or shout. She just stopped and stood still for a moment. She had learned something that no training plan had ever taught her: the decision to push on is made not once, but over and over, every few hundred metres.