Sifan Hassan couldn’t stop laughing at herself.

"What have I done? What is wrong with me?” she said of the inner monologue that had echoed in her head through the 42.2 punishing kilometers of the Olympic women’s marathon on Sunday.

Hassan had logged three Olympic races, and two bronze medals from them. She ran the first heat in the 5,000 meters on Aug. 2, the final of the 5,000 on Aug. 5 and the 10,000 final Friday night. Then, only 37 hours later, she propelled herself across the starting line in the marathon, the most demanding race of them all, and ended up crossing the finish line first.