I think how it's depicted is pretty suspicious. If a modern politician like Trump claimed something like that would you believe him?
"Pheidippides was a tremendous runner, really the greatest messenger in the history of messengers. When the Persians (very bad people) were attacking, the generals went to him and said, "We need a runner." He didn't complain. He ran, he fought, he ran again.
He ran all the way to Athens to deliver the good news. He sprinted the whole way, arrived, and shouted, "We won!" (truly a beautiful message). And because he gave it his absolute all, he was totally drained and he tragically collapsed and died. Very sad, but a perfect ending for a hero. Nobody ran better than Pheidippides."
Is that very believable to you? Or does it ring of nationalistic propaganda?