Long distance relationships?

I'm from California and I met this guy that lives in South Korea. At first I didn't think of it as anything because the whole idea is just insane. But we've been talking every single day and I'm starting to get feelings for him, he's a pathologist in his country and im studying to be a dentist so being together in the long run might be hard. The time difference is also something I can't get used to, SK is 16 hours ahead. So when it's afternoon here, it's morning time over there. Anyways, have any of you been in a LDR? How did it workout? Any advice?