The reason why Ji Changwook is being grateful towards Yoona

is because Yoona is not heavy.

There was a scene where Ji Changwook had to run and jump over a cary while carrying Anna.

(The Gif)

*points to Ji Changwook* : A cool Oppa

Ji Changwook: Thanks for being so light, I'll treat you a meal.

caption : Im Yoona already had lunch (before the scene)

 But Yoona grabbed his collarㅋㅋㅋ

*caption on Ji Changwook*: *nods* I'm fine. 

caption: Stop breathing (very loudly)!!! 

instiz

-Whoa.. Look at his smile..

-Ji Changwook is such a very sweet guy..

-So sweetㅠㅠ

-They both are equally cuteㅋㅋㅋ

-Whoa.. Brb crying..

-The way he laughs is so cuteㅋㅋ Anyway, Yoona is too skinny..

-'I'll treat you a meal'.. The way he says that is so heart-fluttering..ㅠㅠ

-What drama is this?

-Changwookie..

-Just imagine how light Yoona is..

-Yoona is so pretty.. I mean it..

-Horray for Ji Changwookㅠㅠㅠ

-I'm watching TheK2 because of them..ㅠㅠ

-Whoa.. But she really does look so light..

-Both of them are so good-looking..

-Seems like Yoona has a really nice personalityㅠㅠ Does she lack in anything..

-I can already feel how light Yoona is just by seeing how Changwook carries her..

-Look at both of their visuals..

-He's so freaking handsome..

-How much does Yoona weight? She looks so thin..

-Ji Changwook is very handsome..

-Yoona-ya.. Grab my collar too..