Runners can train for months just to be fit enough to jog a 5k, let alone a half marathon – but this young teen didn't seem to break a sweat.

LeeAdianez Rodriguez-Espada rushed to the starting line of what she thought was the Flower City Marathon's 5k race which she had registered for, but when she was on her fourth mile, she started to wonder if something was wrong.

Instead of joining the three mile race as she intended, she leapt into the half-marathon – which requires ten miles of further endurance, than what she practiced.

Lee, however, decided to finish it anyway, earning herself a medal for completing the extra distance.

"I see her with a medal and I thought, ‘Oh my gosh, she ran the other one, like for real,'" Lee's mom Brendalee told WHAM. "She is just 12-years-old and she decided to just keep running and not giving up."

The accidental athlete finished the Rochester, New York half-marathon at two hours and forty-three minutes after taking up running only two months earlier.

(WATCH the Associated Press video below)

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