You could look through the following threads: 
Personally, I can’t recall any at the moment. Hope you find some good ones!
From 18 Again, since that’s the latest memorable one I watched:
“No matter how hard life gets, never regret anything that made you smile.”
“Do not let people who do not know you get to you.” - Ye Ji Hoon’s brother
“If you are serious about your dream, no matter how hard it gets, I hope you will take good care of yourself.” - Jung Da Jung
“If you keep it in, the strong will get stronger and the weak will become weaker. When you need to fight, you should.” -Hong Dae Young
“No matter how old you get, there is always something new to learn. If you think of it as a regret, that is the end of it. But when you think of it as a lesson learned, it brings a new beginning. I will try to learn more from now on, whether it is about work, life, or love. So, I will try to find what I love to do again… I am going to spend my life without any regrets.” -Hong Dae Young
“There’s nothing to fear when we only live once. We have to be bold and do whatever we want to do in life.” -Hong Dae Young