It's a sad, sad day for K-pop fans as Super Junior's Siwon and TVXQ's Changmin both began their mandatory military service today. Siwon is leaving on a high note, having just wrapped up the ratings hit She Was Pretty, where many viewers (*raises hand*) felt he completely stole the show. As we bid farewell to Siwon, let's take a look at some of the things we'll miss most while he's away.

1. His expressive face

This is what endeared me most to Siwon in his latest role. I will never, ever get tired of Siwon's many derp faces.

2. His ability to bring the feels

Yes, Siwon is mostly known for being funny, but his acting range has seriously grown over time. Some of the heartbroken looks he gave in She Was Pretty gave me a serious case of allergies in my eyeballs.

3. He doesn't take himself too seriously

Siwon may be a star, but if you follow him on Instagram or watch him in interviews, he never really takes himself too seriously. He's always joking around, and he's not afraid of looking completely ridiculous. One of my favorites was when a fan posted a photo of embarrassing spotlight placement during a show, and instead of getting upset, Siwon just ran with it.

4. His caring heart

Siwon has been involved with various UNICEF causes since 2010, and on November 10, 2015, he was named a special representative for the charitable organization's Korean branch. I love seeing stars who give back!

5. His many talents

Drama fans found Siwon through his acting, but there are many ELFs out there who first fell in love with Siwon as a member of Super Junior. He can sing, he can dance — Is there anything he can't do? If you want to see his moves in action, check out Super Junior in the KCON LA concert below:

6. His...ABpreciation for fitness

Look — he just really wants to promote health, okay?

7. His strong beard game

Never shave, Siwon.

8. His impressive cosplay repertoire 

Halloween has always been one of my favorite holidays, so I especially love how Siwon goes all-out with his costumes. Like that time he dressed as a magnificent centaur.

9. His charisma

Some stars really just have that "it" factor, and Siwon is one of them. Every time he does a photo shoot or an interview, he has that magnetic ability to draw attention that goes beyond his handsome looks.

10. His dedication to his dog

Siwon's relationship with his dog Bugsy is pretty much the cutest thing ever. If you haven't seen the back-and-forth Twitter battle between Bugsy and Eunhyuk;s dog Choco (who sadly died earlier this year), you absolutely should.

Siwon already bid farewell to his furry friend on Instagram, posting the photo below with the caption, "It's ok buddy, it's only 2 years :)" Ack! My heart!

What will you miss most about Siwon? Really, there's only one thing left to say:

Good luck, Siwon, and return home safely! We will be anticipating your return! 

If you need one last Siwon fix to tide you over, you can see him in She Was Pretty below:

And if you need some good news to lift your spirits, remember that military enlistment doesn't last forever! Here are 7 currently enlisted stars who will be returning home next year.