I watched this movie for the first time a couple years ago. I remember liking it a lot, but I wasn't sure if it was just because it's one of the first BLs I watched, or because it was actually good.
Now that I watched it again I can confirm that, yes, I loved it.

- First of all, the story mainly revolves around marathons and I appreciated the fact that they didn't just use it as an aesthetic. It might sound obvious, but I've seen way too many movies and dramas where they start with a theme, only to put it aside and turn the story into something entirely different. Here the characters run all the time, make plans about marathons, worry about training and taking proper care of their bodies, all without neglecting the romance.
- Secondly, the main characters were great. Both the actors did a very good job portraying them - Han Se Jin in particular shines at all times, he did amazing and he made me want to watch other productions where he's part of the cast. Since Sang Ha and Jin Won are so different I was worried that the romance between the two would feel forced in some way, but instead I believe it was paced pretty well. Seeing Jin Won slowly but steadily warming up to Sang Ha and then caring for him and wanting him by his side was very satisfying. The problems they had were not the usual annoying couple misunderstandings or lack of communication either.
- There was no time wasted, at ANY time. Every single scene felt important for the sake of the plot or the character introspection. One could argue that the ending could use some more screen time, but to be honest I'm satisfied.

This one will stay in my heart and I'll probably end up considering it a classic as time goes by.