Now, either we're all just becoming really grumpy as we get older, or it may mean that as you understand laughter better, and you are getting better at doing that, you need more than just hearing people laugh to want to laugh.
나이가 들면서 더 퉁명스러워지든 아니면 웃음을 더 잘 이해하게 되든 더 잘 이해하게 됩니다. 웃고 싶어지려면 웃음 소리를  듣는 것 이상을 해야 합니다.