Yuki Kawauchi, 2018 Boston Marathon Champ

Until his victory in Boston, Kawauchi, a full-time civil servant in Japan, was an amateur, crisscrossing the globe on his own dime in the process of setting Guinness records for the most marathons under 2:12 (26) and 2:20 (79). Within hours of winning his first major, he announced his intention to turn pro. Check out this article about him from The Guardian, which includes clips of him running an unofficial world record for the half in a business suit, finishing in the same race a year later wearing a panda suit, and running possibly the fastest marathon in the coldest conditions at Marshfield in January.