This was such a cute, light-hearted, short show. I found the story of a runner and pacemaker refreshing. The bl genre is so full of engineer college students, this was a breath of fresh air.
I do think that it was not brought to it's full potential because it was so short. I would love to see this in a full series of 22 episodes w/ 40 mins per and see how much more the story develops.
When I learnt about the debt collectors, I got excited to see some drama and Jin Won showing strong emotions when learning about Sang Ha's situation but we got none of that and it was pushed aside as if it were nothing big. If we had longer episodes for this I would also love to see Sang Ha working day and night to fulfill the debt collector boss' request of winning the marathon and not him just winning it out of nowhere.
Now, granted I have a horrible memory but as I'm writing this, I just watched the show in it's entirety and I can't remember anything interesting or characteristic about Jin Won other than his want/need to be faster and that he can have a bit of a temper. With Sang Ha, It's a bit opposite as we learn about his past, more or less, along with his more expanded personality.
Overall great, would have been better with more time and without rushing.
If you're the type to read spoiler comments before watching, give it a watch if you have roughly 80 minutes and want something light and cute. Will recommend, was a fun series.

Apologies if you noticed this review was a bit all over the place.